pii: sp-00769-14
http://dx.doi.org/10.5665/sleep.5170
DEVELOPMENT OF THE SLEEP PROBLEM ACCEPTANCE QUESTIONNAIRE
Measuring Acceptance of Sleep Difficulties: The Development of the Sleep Problem Acceptance Questionnaire Kristoffer Bothelius, MSc1; Susanna Jernelöv, PhD2; Mats Fredrikson, PhD1; Lance M. McCracken, PhD3; Viktor Kaldo, PhD2 Department of Psychology, Uppsala University, Uppsala, Sweden; 2Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; Health Psychology Section, Psychology Department, Institute of Psychiatry, King’s College London, London, UK
1 3
Study Objectives: Acceptance may be an important therapeutic process in sleep medicine, but valid psychometric instruments measuring acceptance related to sleep difficulties are lacking. The purpose of this study was to develop a measure of acceptance in insomnia, and to examine its factor structure as well as construct validity. Design: In a cross-sectional design, a principal component analysis for item reduction was conducted on a first sample (A) and a confirmatory factor analysis on a second sample (B). Construct validity was tested on a combined sample (C). Setting: Questionnaire items were derived from a measure of acceptance in chronic pain, and data were gathered through screening or available from pretreatment assessments in four insomnia treatment trials, administered online, via bibliotherapy and in primary care. Participants: Adults with insomnia: 372 in sample A and 215 in sample B. Sample C (n = 820) included sample A and B with another 233 participants added. Measures: Construct validity was assessed through relations with established acceptance and sleep scales. Results: The principal component analysis presented a two-factor solution with eight items, explaining 65.9% of the total variance. The confirmatory factor analysis supported the solution. Acceptance of sleep problems was more closely related to subjective symptoms and consequences of insomnia than to diary description of sleep, or to acceptance of general private events. Conclusions: The Sleep Problem Acceptance Questionnaire (SPAQ), containing the subscales “Activity Engagement” and “Willingness”, is a valid tool to assess acceptance of insomnia. Keywords: acceptance, experiential avoidance, insomnia, principal component analysis, psychometric evaluation, scale construction, Sleep Problem Acceptance Questionnaire, willingness Citation: Bothelius K, Jernelöv S, Fredrikson M, McCracken LM, Kaldo V. Measuring acceptance of sleep difficulties: the development of the sleep problem acceptance questionnaire. SLEEP 2015;38(11):1815–1822.
INTRODUCTION The concept of acceptance, the capacity to make an active choice to be more open toward psychological experiences,1 has gained popularity and scientific support within behavioral medicine.2 Acceptance has been most extensively studied in relation to chronic pain,3,4 but also in diabetes,5 epilepsy,6,7 fatigue,8,9 smoking cessation,10,11 stuttering,12 and tinnitus,13,14 among other conditions. In behavioral medicine, acceptance has been shown to be a key therapeutic process mediating the effect of treatment methods on outcome, for example, in the treatment of chronic pain15,16 and tinnitus.17 Identifying mediators of change may improve understanding of the nature of health problems as well as enhance treatment effects.18 An area where acceptance may also be relevant, but has not yet been systematically investigated, is the area of insomnia or sleep problems more generally.19–22 Acceptance is an important target for the therapeutic process in acceptance-based treatments. Acceptance and avoidance are counterparts, where “experiential avoidance” in particular, is defined as attempts to control or limit contact with distressing thoughts, feelings or other aversive internal
Submitted for publication December, 2014 Submitted in final revised form April, 2015 Accepted for publication May, 2015 Address correspondence to: Kristoffer Bothelius, MSc, Department of Psychology, Uppsala University, Box 1225, 751 42 Uppsala, Sweden; Tel: +46 70 398 12 13; Fax: +46 18 50 35 39; Email: kristoffer.bothelius@ psyk.uu.se SLEEP, Vol. 38, No. 11, 2015
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experiences. Such avoidance reduces discomfort momentarily, but may lead to long-term negative consequences.23 Preventing experiential avoidance and facilitating experiential exposure, including emotional exposure, seems to be one of the fundamental therapeutic components within a range of empirically supported psychological treatments.24 Within an acceptancebased framework, the pathological process that drives insomnia could be described as beginning with the unpleasant experience of being awake at night when one wants to be sleeping, and being tired in the daytime when one wants to be energetic.25 To avoid these experiences one may then adopt a number of behavior patterns, such as spending excessive time in bed trying to sleep, daytime napping, or other patterns that constitute an irregular sleep-wake schedule.26 Unfortunately, these behavior patterns interfere with homeostatic and circadian mechanisms, and can result in a conditioned arousal in the bed and bedroom, which maintains sleep problems.27 Thus, attempts to avoid disturbing experiences related to insomnia can paradoxically feed the insomnia itself. An alternate behavior pattern would be to be open and accepting of the experiences of insomnia, which can certainly stop the struggling to fall asleep, and possibly improve sleep. In order to address the possible role of acceptance in relation to insomnia, a measure of acceptance of sleep problems, such as insomnia, is needed. General tools for measuring acceptance have been developed, for example, the Acceptance and Action QuestionnaireII.28 However, specific instruments are often more responsive to change than generic instruments,29 and may better reflect processes conceptualized in relation to a specific problem area. In addition, it has been recommended that such instruments The Sleep Problem Acceptance Questionnaire—Bothelius et al.
should be as short as possible, to minimize the burden on respondents.30–32 There is an example of a well-developed specifically focused instrument for measuring acceptance in chronic pain, the 20-item Chronic Pain Acceptance Questionnaire (CPAQ). It was originally based on a pool of 34 items.33 The questionnaire is now extensively studied34 and shown to have a two-factor structure assessing Activity Engagement (i.e., engaging in activities in the presence of pain) and Pain Willingness (i.e., refraining from attempts to control or reduce pain).35 The questionnaire has been adapted for use with tinnitus and fatigue, and these adaptations have kept a similar two-factor structure.36,37 For studying acceptance in insomnia, we aimed to develop a new assessment instrument that we now refer to as the Sleep Problem Acceptance Questionnaire (SPAQ). The goal for this measure was to gain the ability to examine the role of acceptance in relation to variables that reflect quality of sleep, and also to determine whether acceptance could be a treatment process variable. It was deemed desirable that the questionnaire resemble similar acceptance questionnaires used successfully in other behavioral medicine contexts. The purpose of the current study was to investigate the item content and factor structure, internal consistency, and construct validity of the SPAQ. We predicted that the results would reflect a two-factor structure found in subjects with chronic pain, tinnitus, and fatigue as previously described, and this is also in line with central constructs in acceptancebased theory: “willingness” (i.e., being fully in contact with the present moment) and “committed action” (i.e., persisting with or changing behavior in the pursuit of goals and values).1 Because acceptance of tinnitus mediates the effect of subjective tinnitus loudness on tinnitus distress,38 and acceptance of chronic pain mediates the effect of pain severity on pain interference,39 we predicted that acceptance of sleep problems would more closely relate to the subjective experience of the disturbance than to descriptive aspects of sleep (such as sleep onset latency and wake time after sleep onset). It was hypothesized that the SPAQ should correlate positively with other measures of acceptance and negatively with subjective insomnia severity. It was also hypothesized that the SPAQ would be negatively correlated with sleep onset latency and wake time after sleep onset. METHODS Design A principal component analysis (PCA) was conducted on a first sample (A) to reduce the number of items, and this was followed by a confirmatory factor analysis on a second sample (B). Construct validity was assessed on a combined sample (C) through regression analyses and correlations with established measures of acceptance, insomnia, and other sleep related factors. Participants Sample A consisted of screening assessments of 372 subjects applying for two studies of Internet-delivered cognitive behavioral therapy for insomnia,40,41 72% women, mean age 42.0 (standard deviation [SD] = 15.0). Education level: compulsory school 5.5%, upper secondary school 26.6%, and SLEEP, Vol. 38, No. 11, 2015
college/university 67.9%. The study protocol was approved by the regional ethical review board in Stockholm (Diary No. 2009/1810-31/3), and is registered at ClinicalTrials.gov, registration ID: NCT01256099. Sample A+ includes these 372 participants, and an additional 233 who were screened after the PCA had already been performed, resulting in 605 participants. In sample B (total n = 215) subjects from two trials were merged: (I) Pretreatment assessments of 156 media recruited adults with primary or comorbid insomnia participating in a bibliotherapy study,42 75% women, mean age 50.8 (SD = 11.8). Education level: compulsory school 4.5%, upper secondary school 29.5%, and college/university 65.9%. The study protocol was approved by the regional ethical review board in Stockholm (Diary No. 2008/23-31/4), and is registered at ClinicalTrials. gov, registration ID: NCT01105052. (II) Pretreatment assessment of 59 adults with primary or comorbid insomnia participating in a randomized controlled study of manual-guided cognitive behavior therapy for insomnia, delivered by ordinary primary care personnel in general medical practice,43 90% women, mean age 50.7 (SD = 11.7). Education level: compulsory school 27.6%, upper secondary school 51.7%, and college/university 20.7%. The study protocol was approved by the regional ethical review board in Uppsala (Diary No. 2008/080), and is registered at ClinicalTrials. gov, registration ID: NCT01655797. There was no statistically significant difference in age between sample A (mean = 47.0, SD = 15.0) and sample B (mean = 48.2, SD = 13.4), t(489.9) = 1.00, P = 0.32, nor sex, χ2(1, n = 587) = 3.19, P = 0.07, but education level was higher in sample A, χ2(2, n = 575) = 33.66, P < 0.001. Subjects from sample A+ were merged with subjects in sample B, forming sample C, composed of 820 subjects. All subjects were screened for other common untreated sleep disorders in diagnostic interviews. Measures Instrument Development
The first two authors (KB and SJ) reviewed the 34 original items behind the CPAQ, derived from Geiser,44 together with a sleep expert (Jan-Erik Broman, PhD). Despite the fact that all 34 items have not been used in any established version of the CPAQ, they were considered to have potential relevance for insomnia and were included in the initial principal components analysis. KB and SJ then translated all items to Swedish and adapted them to insomnia. The items were backtranslated into English and one of the authors (LM) then approved the backtranslation from theoretical as well as semantic aspects. The adaption was quite straightforward; most of the time by simply exchanging “pain” with “sleeping problems”. This formulation is in line with other measures of insomnia, for example, the widely known Insomnia Severity Index.45 For example, the item reading “although things have changed, I am living a normal life despite my chronic pain” was changed to “although things have changed, I am living a normal life despite my sleeping problems.” Like the CPAQ, each item is rated on a 0- to 6-response scale. For the SPAQ, 0 equals “disagree” and 6 equals “completely agree.” Items for which a
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high score implicates low acceptance are reversed in all statistical evaluations so that a high total score reflects a high level of acceptance. Because our objective was a short questionnaire free from items with unclear wording, we wanted to reduce the number of items in an initial principal components analysis.
number of items per scale dimension,53,54 with at least four items in each subscale.55 The item reduction was performed stepwise, starting with excluding the items with the lowest factor loading. Items with low standard deviations, double loadings, or that were considered theoretically ambiguous were also removed.
Additional Measures
Confirmatory Factor Analysis
Acceptance and Action Questionnaire-II: The Acceptance and Action Questionnaire-II (AAQ-II)28 is a seven-item scale mostly focused on general psychological acceptance of private events. All of the items are negatively keyed, so it is sometimes referred to as a measure of experiential avoidance. In the current study lower scores indicate higher acceptance. Insomnia Severity Index: The Insomnia Severity Index (ISI)45 is a widely used, reliable, and valid46 seven-item selfreport measure for insomnia, targeting subjective symptoms, consequences of insomnia, and distress. A high total score indicates a high level of perceived sleep difficulties. Dysfunctional Beliefs and Attitudes about Sleep Scale: The Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS)47 is a 30-item self-report questionnaire evaluating sleep-disruptive cognitions. A higher score indicates more unhelpful cognitions. Sleep-Related Behaviours Questionnaire: The 32-item Sleep-Related Behaviours Questionnaire (SRBQ)48 is designed to assess the use of safety behaviors in insomnia (i.e., strategies aiming to prevent a feared outcome, which may in fact be contributing to the maintenance of the disorder). A higher score indicates more safety behaviors. Sleep Diary: Sleep diaries are routinely included in insomnia research. Despite an earlier lack of standardization,49 sleep diaries yield reliable quantification of sleep parameters and are generally recommended for quantitative sleep assessment in insomnia research.50 Sleep diaries give information about the night-to-night variability in sleep timing (bedtimes and rise times), actual time slept (total sleep time, TST), how many minutes it takes to fall asleep (sleep onset latency, SOL), time spent awake during the night (wake time after sleep onset, WASO), and percentage of time in bed spent asleep (sleep efficiency, SE). Analyses The 34 originally adapted items (called SPAQ-34) were included in screening or pretreatment measures in the three insomnia studies in Sweden previously described. Principal Component Analysis
Item reduction was performed using an initial PCA with oblique rotation (direct oblimin), starting with all 34 items on sample A (n = 372). A wide range of recommendations regarding sample size in factor analysis has been proposed. Although there is a lack of agreement regarding rules of thumb, Comrey’s guide suggesting a minimum of 300 subjects51 and Nunnally’s heuristic of a subject to item ratio of 10:152 are often cited. Both of these criteria were met. Because we expected a two-factor solution, we restrained the number of factors to two. We wanted a short questionnaire but still followed the recommendations that measures have an equal SLEEP, Vol. 38, No. 11, 2015
To confirm the factors suggested by the PCA, structural equation modeling (SEM) was used to perform a confirmatory factor analysis (CFA) using sample B, n = 215. There is no simple rule regarding minimum sample size in a CFA, but having at least 200 subjects is advised.56 The AMOS software package (version 22.0)57 was used for the CFA. To complement the basic Chi-2 model fit test (testing if there is a difference between the model and the data), which is known for being very conservative except for small sample sizes, the following model fit indices and cutoff values were used: root mean square error of approximation (RMSEA < 0.08), comparative fit index (CFI > 0.95), standardized root mean square residual (SRMR < 0.09), and the Chi-2 value divided by the degrees of freedom (Chi-2/df < 3).58–61 Construct Validity
Construct validity was assessed by examining the relations with variables known to be theoretically linked with acceptance of insomnia. In these analyses, sample A+ was merged with sample B forming sample C, amounting to 820 subjects. To maximize power, missing data were excluded pairwise. The Kolmogorov-Smirnov test showed data on SOL, WASO, and SE derived from sleep diaries to be significantly different from a normal distribution. This sleep diary data were therefore logarithmically transformed, which normalized distribution, before correlations were computed. To analyze the unique contribution of the SPAQ on insomnia, a multiple regression was performed, with ISI score as an outcome variable and the SRBQ, the DBAS, and the SPAQ as predictors. RESULTS Principal Component Analysis The principal component analysis was performed on sample A. The reduction of items was performed in two steps and a final solution with two four-item factors was presented. The scree plot and the criterion of an eigenvalue above 1 supported this solution, and the theoretical and statistical adequacy of the items in each factor were inspected and found satisfactory. Thus, the solution presented in Table 1 was chosen. The content of the two subscales was deemed to be well in line with the corresponding subscales in the original CPAQ and hence similar labeling of the subscales was used, i.e., “Activity Engagement” and “Willingness”. The Kaiser–Meyer–Olkin Measure of Sampling Adequacy was found to be 0.83, which is considered good.62 The solution explained 65.9% of the total variance among all eight items. The Cronbach α of the two four-item subscales, 0.89 for Activity Engagement and 0.73 for Willingness, were deemed satisfactory.63 The Cronbach α for the scale as a whole was lower, 0.55. The correlation between the two subscales was r = 0.22.
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Table 1—Rotated factor loadings for the exploratory two-factor solution. Item 1 2 3 4 5 6 7 8
Content summary Although things have changed, I am living a normal life despite my sleeping problems. I lead a full life even though I have sleeping problems. My life is going well, even though I have sleeping problems. Despite the sleeping problems, I am now sticking to a certain course in my life. Keeping my sleeping problems under control takes first priority. I need to concentrate on getting rid of my sleeping problems. It’s important to keep on fighting these sleeping problems. My thoughts and feelings about my sleeping problems must change before I can take important steps in my life.
Factor 1 0.88 0.87 0.84 0.84 −0.16 −0.061 0.17 −0.18
Factor 2 −0.056 −0.003 −0.076 −0.003 0.78 0.79 0.77 0.61
n = 372.
Table 2—Correlations between the Sleep Problem Acceptance Questionnaire (SPAQ) subscales (Activity Engagement and Willingness), the total SPAQ score, and the Insomnia Severity Index (ISI), sleep onset latency (SOL), wake time after sleep onset (WASO), total sleep time (TST), sleep efficacy (SE), the Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS), and the Sleep-Related Behaviours Questionnaire (SRBQ).
Activity Engagement Willingness Total SPAQ-score a
ISI (n = 815) −0.449 b −0.450 b −0.563 b
AAQ II (n = 599) −0.382 b −0.193 b −0.368 b
SOL (n = 377) −0.139 a −0.078 −0.149 a
WASO (n = 187) −0.122 −0.245 a −0.223 a
TST (n = 377) −0.039 0.080 0.082
SE (n = 375) 0.087 0.050 −0.091
DBAS (n = 195) −0.397 b −0.410 b −0.514 b
SRBQ (n = 195) −0.534 b −0.373 b −0.594 b
P < 0.01. b P < 0.001.
was significant (χ2(19) = 45.8, P = 0.001), but this is very common for large sample CFAs.64 Overall, the support for the model was seen as sufficient considering that all other indicators were deemed strong or satisfactory, and we decided to let the initial model also be the final model presented in Figure 1. The Cronbach α for the whole measure was 0.59.
Figure 1—Structural equation model for the Confirmatory Factor Analysis for the final version of the Sleep Problem Acceptance Questionnaire.
Confirmatory Factor Analysis The initial model with two factors was tested on sample B in a confirmatory factor analysis. The SRMR (0.063), the CFI (0.96), and the Chi-2/df (2.4) indicated adequate fit. The RMSEA (0.081) was just above the threshold. The Chi-2 test SLEEP, Vol. 38, No. 11, 2015
Construct Validity For assessing construct validity, the newly developed SPAQ was correlated against existing measures of insomnia and acceptance related constructs, see Table 2. The SPAQ correlated negatively with the ISI and the AAQII. In the AAQ-II lower scores indicate higher acceptance so this correlation is actually positive. The AAQ-II also correlated with the ISI, but to a lesser extent, r = 0.237, P < 0.001. The SPAQ correlated negatively with WASO and SOL derived from sleep diaries (but not with TST or SE), the DBAS, and the SRBQ. The Activity Engagement subscale correlated negatively with SOL and the Willingness subscale correlated negatively with WASO. Both subscales correlated negatively with the ISI, the AAQ-II, the DBAS, and the SRBQ. A multiple regression (forced entry in two steps) showed that in step 1, both the SRBQ and DBAS significantly predicted ISI score and together they predicted 17% of the variance. When the SPAQ was added in the second step, the total predicted variance increased significantly (P < 0.001) by another 15% and only the SPAQ remained a significant predictor (Table 3). We therefore re-performed these analyses, but separately adding the two subscales of SPAQ to the SRBQ and the DBAS. When “Willingness” was added in the second step (B = −0.20, P = 0.001), the SRBQ remained significant (B = 0.05, P = 0.03), but not the DBAS. When the “Activity Engagement” subscale was added 1818
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instead in step 2 (B = −0.24, P < 0.001) the DBAS was still significant (B = 0.02, P = 0.02), but not the SRBQ. In sample A+ mean value for the total SPAQ score was 20.23 (SD = 8.37), for the Activity Engagement subscale 11.97 (SD = 5.77), and for the Willingness subscale 8.25 (SD = 4.66). In the bibliotherapy study mean value for the total SPAQ was 17.16 (SD = 8.09), for the Activity Engagement subscale 9.26 (SD = 5.46), and for the Willingness subscale 7.90 (SD = 4.96). In the primary care study mean value for the total SPAQ was 18.47 (SD = 9.11), for the Activity Engagement subscale 12.03 (SD = 5.70), and for the Willingness subscale 6.44 (SD = 5.21). DISCUSSION The aim was to develop and validate a brief measure of acceptance of sleep problems. This resulted in the SPAQ, an eight-item questionnaire with two factors, Willingness and Activity Engagement. To our knowledge, this is the first specific measure of acceptance in insomnia. This structure is in agreement with two-factor solutions found for similar acceptance questionnaires used in chronic pain, tinnitus, and fatigue, and our labeling of the subscales as Activity Engagement and Willingness was in line with these other measures. An analysis of construct validity shows that the SPAQ has a strong negative correlation with the ISI, but only a weak negative correlation with SOL and WASO, and no correlation with SE or TST. This is somewhat in line with what was predicted; low acceptance of insomnia is more closely related to subjective effect of severe sleeping problems, than to more descriptive aspects of the sleep (e.g., long time awake during the night and short sleep length). The negative correlation between the SPAQ and the negatively keyed AAQ-II (in fact a positive correlation) was medium sized, whereas the correlation between the AAQ-II and the ISI was small. The insomnia-specific measure of acceptance, SPAQ, hence seems to correlate fairly well to the more general acceptance questionnaire AAQII, while at the same time correlating more closely with the subjective symptoms and consequences of insomnia than the AAQ-II manages to do. A negative correlation with the AAQII is expected because this measure is theoretically reversed and reflects avoidance. The SPAQ correlates highly negatively with both the DBAS and the SRBQ, indicating that lower acceptance of insomnia is closely related to more sleep-disruptive beliefs, attitudes, and safety behaviors. As shown in the multiple regression analysis, the SPAQ reflects a unique concept that may be of importance for understanding perceived insomnia severity and for guiding psychological treatment for insomnia. Activity Engagement means persistence with normal activities, even when sleep is perceived as not being satisfying, whereas Willingness reflects refraining from attempts to fight sleep problems and control sleep. These scales mirror the central theoretical construct in acceptance-based therapies: “psychological flexibility.” This construct, in turn, reflects the ability to experience the current moment without trying to change it and to engage in personally important activities; again, both when it is easy to do this but particularly when one encounters potential barriers such as unwanted or discouraging thoughts and feelings.1 In insomnia this could be SLEEP, Vol. 38, No. 11, 2015
Table 3—Multiple regression with the Insomnia Severity Index as outcome variable, the Dysfunctional Beliefs and Attitudes about Sleep and the Sleep-Related Behaviours Questionnaire as predictors in step 1, and the Sleep Problem Acceptance Questionnaire added in step 2. Step 1 Constant DBAS SRBQ
B
SE B
β
9.21 0.03 0.06
1.42 0.01 0.02
0.22a 0.23a
Step 2 Constant DBAS SRBQ SPAQ
20.37 0.01 0.00 −0.22
2.13 0.01 0.02 0.03
0.11 (ns) 0.00 (ns) −0.50b
R 2 = 0.17 for Step 1, ΔR2 = 0.15 for Step 2 (P < 0.001). aP < 0.01. b P < 0.001. DBAS, Dysfunctional Beliefs and Attitudes about Sleep; ns, not significant; SRBQ, Sleep-Related Behaviours Questionnaire; SPAQ, Sleep Problem Acceptance Questionnaire.
translated to willingness to experience nonoptimal sleep, and to direct energy toward personally important goals despite resistance, instead of fighting or trying to control insomnia. An instrument to assess acceptance, and it subcomponents, in insomnia is necessary to examine the relations between acceptance, suffering, and treatment outcome. The results suggest that these two subscales represent a whole process and both ought to be included when one is interested in acceptance in insomnia. Acceptance is an active choice. In other behavioral medicine disciplines there is accumulating evidence that pursuing valued activities may be a more successful approach to chronic diseases, as opposed to fighting against or trying to avoid unpleasant symptoms.2 Although fighting or avoiding unwanted experiences might result in temporary relief from these symptoms, this form of experiential avoidance may result in increased interference with life in the long run. In chronic pain research there are data showing that low acceptance is correlated with both high psychological distress and high physical disability,65–67 and in chronic fatigue low acceptance has been shown to relate to high psychological distress9 and to predict low physical functioning.8 The role of acceptance in insomnia could be, as with diabetes,5 both an important mediator of change, and a desired outcome following treatment. From a purely theoretical standpoint however, acceptance is never the ultimate goal—only a way to approach life in tune with one’s values.1 Likewise, symptom reduction is not an end goal of acceptance-based treatment, but such treatment has nonetheless been shown to reduce the number of epileptic seizures6,7 and reduce overall frequency of stuttering,12 showing that acceptance is not merely an inert response to symptoms, or passive resignation. One possible difference between acceptance in insomnia and acceptance in, for example, chronic pain and tinnitus is in the willingness factor. In tinnitus and chronic pain this factor seems to be characterized by control and avoidance, whereas in insomnia there is more of control and fight. One item that is unique for the SPAQ is: “It’s important to keep
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on fighting these sleeping problems,” and in contrast with the CPAQ and the Tinnitus Acceptance Questionnaire (TAQ)36 items do not include conventional avoidance behavior patterns. One could speculate there might be different qualities in the acceptance behaviors that are most typical for different underlying conditions. For example, passive avoidance and withdrawal may relate more to depressive behavior problems in chronic pain and tinnitus, and require greater behavioral activation as a therapeutic response,68 whereas a more actionoriented fighting style of avoidance in insomnia may lend itself to problems with states of hyperarousal69 and a dysregulated stress system,70 thus requiring different therapeutic methods that reduce the effect of thoughts and feelings on behavior. It is worth emphasizing the potential value of an assessment instrument that can provide reliable and valid data regarding acceptance of insomnia. Currently, in most areas of cognitive behavioral therapy, there is an increased interest in therapeutic process, or active mechanisms of treatment effect. Aspects of psychological flexibility, such as acceptance, appear to hold great potential as process variables that can help us to better select, target, and optimize methods for addressing problems such as sleep disturbance and insomnia.4 The study has some limitations that deserve mention. The four-plus-four-item version that the authors advocate is based on statistical considerations, as well as a theoretical discussion of balancing two important constructs. Because the questionnaire contains two different factors, the Cronbach α for the whole scale is low, and it is important to consider the subscales separately when interpreting the scores.71 The study did not assess the test-retest reliability of the measure or its sensitivity to change, and it did not produce clinically relevant cut-off scores that allowed for individual scores to be classified as high or low. Even if the SPAQ shows significant correlations with other insomnia specific measures, these correlations cannot support conclusions regarding causality, and it is possible that the relations are bidirectional. Finally, all subjects had a verified insomnia diagnosis and were seeking treatment. It is possible that a population not seeking treatment or with subthreshold insomnia may have responded differently. A merit of the study is that the factor structure is validated on a separate sample. Future studies might assess the prognostic value of SPAQ scores for different insomnia treatments and explore whether acceptance of sleep problems can explain some of the differences between descriptive sleep measures and subjective insomnia severity, in line with how tinnitus-specific acceptance partially mediates the relation between subjective tinnitus loudness and tinnitus distress,38 and how pain-specific acceptance partially mediates the relation between pain severity and pain interference.39 To conclude, the SPAQ seems to be a theoretically adequate and statistically sound measure of acceptance in people with insomnia. In future use of the SPAQ, one should consider not only the total score, but also the two subscales. Although insomnia was meant to be the main target of this questionnaire, and represents the primary problem within the samples for which the measure has been developed, the uses of generic sleep concepts in the questionnaire enable studies of acceptance in populations with sleep disturbances other than insomnia. SLEEP, Vol. 38, No. 11, 2015
ACKNOWLEDGMENTS The authors thank Ingrid Andrén, Kerstin Blom, Martin Kraepelien, Kicki Kyhle, Brjánn Ljótsson, Sara Rydh, and Sofi Sjöholm-Jenssen for help with data collection, Sandra Bates for help with the back translation, Sheri Fox for proofreading, and Jan-Erik Broman for help with the development of the SPAQ and valuable comments on the manuscript. DISCLOSURE STATEMENT This was not an industry supported study. Dr. Jernelöv is the author of a commercially available self-help book used in three of the randomized trials from which data were collected. The other authors have indicated no financial conflicts of interest. The work was performed at the Department of Psychology, Uppsala University, Uppsala, and the Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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1. Hayes SC, Luoma JB, Bond FW, Masuda A, Lillis J. Acceptance and commitment therapy: model, processes and outcomes. Behav Res Ther 2006;44:1–25. 2. Prevedini AB, Presti G, Rabitti E, Miselli G, Moderato P. Acceptance and commitment therapy (ACT): the foundation of the therapeutic model and an overview of its contribution to the treatment of patients with chronic physical diseases. G Ital Med Lav Ergon 2011;33:A53–63. 3. Veehof MM, Oskam MJ, Schreurs KM, Bohlmeijer ET. Acceptancebased interventions for the treatment of chronic pain: a systematic review and meta-analysis. Pain 2011;152:533–42. 4. McCracken LM, Vowles KE. Acceptance and commitment therapy and mindfulness for chronic pain: model, process, and progress. Am Psychologist 2014;69:178–87. 5. Gregg JA, Callaghan GA, Hayes SC, Glenn-Lawson JL. Improving diabetes self-management through acceptance, mindfulness, and values: a randomized controlled trial. J Consult Clin Psych 2007;75:336–43. 6. Lundgren T, Dahl JA, Melin L, Kies B. Evaluation of acceptance and commitment therapy for drug refractory epilepsy: a randomized controlled trial in South Africa - a pilot study. Epilepsia 2006;47:2173–9. 7. Lundgren T, Dahl J, Yardi N, Melin L. Acceptance and Commitment Therapy and yoga for drug-refractory epilepsy: a randomized controlled trial. Epilepsy Behav 2008;13:102–8. 8. Brooks SK, Rimes KA, Chalder T. The role of acceptance in chronic fatigue syndrome. J Psychosom Res 2011;71:411–5. 9. Van Damme S, Crombez G, Van Houdenhove B, Mariman A, Michielsen W. Well-being in patients with chronic fatigue syndrome: the role of acceptance. J Psychosom Res 2006;61:595–9. 10. Hernandez-Lopez M, Luciano MC, Bricker JB, Roales-Nieto JG, Montesinos F. Acceptance and commitment therapy for smoking cessation: a preliminary study of its effectiveness in comparison with cognitive behavioral therapy. Psychol Addic Behav 2009;23:723–30. 11. Bricker J, Wyszynski C, Comstock B, Heffner JL. Pilot randomized controlled trial of web-based acceptance and commitment therapy for smoking cessation. Nicotine Tobacco Res 2013;15:1756–64. 12. Beilby JM, Byrnes ML, Yaruss JS. Acceptance and Commitment Therapy for adults who stutter: psychosocial adjustment and speech fluency. J Fluency Dis 2012;37:289–99. 13. Westin VZ, Schulin M, Hesser H, et al. Acceptance and commitment therapy versus tinnitus retraining therapy in the treatment of tinnitus: a randomised controlled trial. Behav Res Ther 2011;49:737–47. 14. Hesser H, Bankestad E, Andersson G. Acceptance of tinnitus as an independent correlate of tinnitus severity. Ear Hear 2015;36:e176–82. 15. McCracken LM, Gutierrez-Martinez O. Processes of change in psychological flexibility in an interdisciplinary group-based treatment for chronic pain based on Acceptance and Commitment Therapy. Behav Res Ther 2011;49:267–74. 16. Wicksell RK, Olsson GL, Hayes SC. Psychological flexibility as a mediator of improvement in acceptance and commitment therapy for patients with chronic pain following whiplash. Eur J Pain 2010;14:1059 e1–11.
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17. Hesser H, Gustafsson T, Lunden C, et al. A randomized controlled trial of Internet-delivered cognitive behavior therapy and acceptance and commitment therapy in the treatment of tinnitus. J Consult Clin Psychol 2012;80:649–61. 18. Kraemer HC, Wilson GT, Fairburn CG, Agras WS. Mediators and moderators of treatment effects in randomized clinical trials. Arch Gen Psychiatry 2002;59:877–83. 19. Lundh LG. The role of acceptance and mindfulness in the treatment of insomnia. J Cogn Psychother 2005;19:29–39. 20. Espie CA, Barrie LM, Forgan GS. Comparative investigation of the psychophysiologic and idiopathic insomnia disorder phenotypes: psychologic characteristics, patients’ perspectives, and implications for clinical management. Sleep 2012;35:385–93. 21. Ong JC, Ulmer CS, Manber R. Improving sleep with mindfulness and acceptance: a metacognitive model of insomnia. Behav Res Ther 2012;50:651–60. 22. McCracken LM, Williams JL, Tang NKY. Psychological flexibility may reduce insomnia in persons with chronic pain: a preliminary retrospective study. Pain Med 2011;12:904–12. 23. Hayes SC, Wilson KG, Gifford EV, Follette VM, Strosahl KD. Experiential avoidance and behavioral disorders: a functional dimensional approach to diagnosis and treatment. J Consult Clin Psych 1996;64:1152–68. 24. Moses E, Barlow DH. A new unified treatment approach for emotional disorders based on emotion science. Curr Dir Psychol Sci 2006;15:146–50. 25. Harvey AG, Tang NK, Browning L. Cognitive approaches to insomnia. Clin Psychol Rev 2005;25:593–611. 26. Morin CM. Cognitive-behavioral approaches to the treatment of insomnia. J Clin Psychiatry 2004;65:33–40. 27. Morin CM. Insomnia: psychological assessment and management. New York: Guilford Press, 1993. 28. Bond FW, Hayes SC, Baer RA, et al. Preliminary psychometric properties of the Acceptance and Action Questionnaire-II: a revised measure of psychological inflexibility and experiential avoidance. Behav Ther 2011;42:676–88. 29. Wiebe S, Guyatt G, Weaver B, Matijevic S, Sidwell C. Comparative responsiveness of generic and specific quality-of-life instruments. J Clin Epidemiol 2003;56:52–60. 30. Edwards P, Roberts I, Sandercock P, Frost C. Follow-up by mail in clinical trials: does questionnaire length matter? Controlled Clin Trials 2004;25:31–52. 31. Nakash RA, Hutton JL, Jorstad-Stein EC, Gates S, Lamb SE. Maximising response to postal questionnaires--a systematic review of randomised trials in health research. BMC Med Res Methodol 2006;6:5. 32. Raubenheimer J. An item selection procedure to maximise scale reliability and validity. J Industr Psychol 2004;30:59–64. 33. McCracken LM, Vowles KE, Eccleston C. Acceptance of chronic pain: component analysis and a revised assessment method. Pain 2004;107:159–66. 34. Reneman MF, Dijkstra A, Geertzen JH, Dijkstra PU. Psychometric properties of chronic pain acceptance questionnaires: a systematic review. Eur J Pain 2010;14:457–65. 35. Vowles KE, McCracken LM, McLeod C, Eccleston C. The Chronic Pain Acceptance Questionnaire: confirmatory factor analysis and identification of patient subgroups. Pain 2008;140:284–91. 36. Westin V, Hayes SC, Andersson G. Is it the sound or your relationship to it? The role of acceptance in predicting tinnitus impact. Behav Res Ther 2008;46:1259–65. 37. Vowles KE. Tired all the time: the role of acceptance in chronic fatigue syndrome. In: Association for Contextual Behavioural Science World Conference III. Enschede, The Netherlands, 2009. 38. Weise C, Kleinstauber M, Hesser H, Westin VZ, Andersson G. Acceptance of tinnitus: validation of the tinnitus acceptance questionnaire. Cogn Behav Ther 2013;42:100–15. 39. Fish RA, McGuire B, Hogan M, Morrison TG, Stewart I. Validation of the chronic pain acceptance questionnaire (CPAQ) in an Internet sample and development and preliminary validation of the CPAQ-8. Pain 2010;149:435–43. 40. Kaldo V, Jernelöv S, Blom K, et al. Guided internet cognitive behavioral therapy for insomnia compared to a control treatment - a randomized trial. Behav Res Ther 2015;71:90–100.
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41. Blom K, Jernelov S, Kraepelien M, et al. Internet treatment addressing either insomnia or depression, for patients with both diagnoses: a randomized trial. Sleep 2015;38:267–77. 42. Jernelov S, Lekander M, Blom K, et al. Efficacy of a behavioral self-help treatment with or without therapist guidance for co-morbid and primary insomnia--a randomized controlled trial. BMC Psychiatry 2012;12:5. 43. Bothelius K, Kyhle K, Espie CA, Broman JE. Manual-guided cognitivebehavioural therapy for insomnia delivered by ordinary primary care personnel in general medical practice: a randomized controlled effectiveness trial. J Sleep Res 2013;22:688–96. 44. Geiser DS. A comparison of acceptance-focused and control focused psychological treatments in a chronic pain treatment center. [Unpublished doctoral dissertation]: University of Nevada, Reno, 1992. 45. Bastien CH, Vallieres A, Morin CM. Validation of the Insomnia Severity Index as an outcome measure for insomnia research. Sleep Med 2001;2:297–307. 46. Morin CM, Belleville G, Belanger L, Ivers H. The Insomnia Severity Index: psychometric indicators to detect insomnia cases and evaluate treatment response. Sleep 2011;34:601–8. 47. Morin CM. Insomnia: psychological assessment and management. New York: Guilford Press, 1993. 48. Ree M, Harvey, AG. Investigating safety behaviours in insomnia: the development of the Sleep-related Behaviours Questionnaire (SRBQ). Behav Change 2004;21:26–36. 49. Carney CE, Buysse DJ, Ancoli-Israel S, et al. The consensus sleep diary: standardizing prospective sleep self-monitoring. Sleep 2012;35:287–302. 50. Buysse DJ, Ancoli-Israel S, Edinger JD, Lichstein KL, Morin CM. Recommendations for a standard research assessment of insomnia. Sleep 2006;29:1155–73. 51. Comrey A. A first course in factor analysis. New York: Academic Press, Inc, 1973. 52. Nunnally JC. Psychometric theory 2nd ed. New York: McGraw Hill, 1978. 53. Durvasula S, Netemeyer RG, Andrews JC, Lysonski S. Examining the cross-national applicability of multi-item, multi-dimensional measures using generalizability theory. J Int Bus Stud 2006;37:469–83. 54. Haberland GS, Dacin PA. The development of a measure to assess viewers’ judgments of the creativity of an advertisement: a preliminary study. Adv Consum Res 192;19:817–25. 55. Netemeyer RG, Bearden WO, Sharma S. Scaling procedures: issues and applications. London: Sage Publications, 2003. 56. Hoyle R. Confirmatory factor analysis. In: Tinsley H, Brown SD, ed. Handbook of applied multivariate statistics and mathematical modeling. San Diego, CA: Academic Press, 2000. 57. Byrne BM. Structural equation modeling with AMOS: basic concepts, applications, and programming. Mahwah, NJ: Lawrence Erlbaum Associates, 2001. 58. Iacobucci D. Structural equations modeling: fit indices, sample size, and advanced topics. J Consum Psychol 2009:90–8. 59. Hu L, Bentler PM. Cutoff criteria for fit indexes in covariance structure analysis: conventional criteria versus new alternatives. Struct Equ Modeling 1999;6:1–55. 60. MacCallum RC, Browne MW, Sugawara HM. Power analysis and determination of sample size for covariance structure modeling. Power analysis 1996;1:130–49. 61. Brown MW, Cudeck R. Alternative ways of assessing model fit. In: Bollen K, Long J, eds. Testing structrual eqation models. Newbury Park, CA: Sage Publications, 1993:136–62. 62. Hair JF. Multivariate data analysis. Upper Saddle River, NJ: Prentice Hall, 1998. 63. DeVellis RF. Scale development: theory and applications. 2nd ed. Thousand Oaks, CA: Sage Publications, Inc., 2003. 64. Ullman JB, Bentler PM. Handbook of psychology, volume 2, research methods in psychology. Hoboken, NJ: John Wiley & Sons, Inc, 2012. 65. McCracken LM. Learning to live with the pain: acceptance of pain predicts adjustment in persons with chronic pain. Pain 1998;74:21–7. 66. McCracken LM, Spertus IL, Janeck AS, Sinclair D, Wetzel FT. Behavioral dimensions of adjustment in persons with chronic pain: pain-related anxiety and acceptance. Pain 1999;80:283–9. 67. Vowles KE, McCracken LM, O’Brien JZ. Acceptance and values-based action in chronic pain: a three-year follow-up analysis of treatment effectiveness and process. Behav Res Ther 2011;49:748–55.
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68. Jacobson NS, Dobson KS, Truax PA, et al. A component analysis of cognitive-behavioral treatment for depression. J Consult Clin Psychol 1996;64:295–304. 69. Roehrs T, Gumenyuk V, Drake C, Roth T. Physiological correlates of insomnia. Current Top Behav Neurosci 2014;21:277–90.
70. Gold PW. The organization of the stress system and its dysregulation in depressive illness. Mol Psychiatry 2015;20:32–47. 71. Cronbach LJ. Coefficient alpha and the internal structure of tests. Psychometrica 1951;16:297–334.
APPENDIX Sleep Problem Acceptance Questionnaire Directions: Below you will find a list of statements. Please rate how much you agree with each statement by marking one alternative. Use the rating scale below to make your choices. 0
1
2
3
4
5
6
Disagree
Almost completely disagree
Slightly agree
Partly agree
Moderately agree
Almost completely agree
Completely agree
1. Although things have changed, I am living a normal life despite my sleeping problems. 2. I lead a full life even though I have sleeping problems. 3. My life is going well, even though I have sleeping problems. 4. Despite the sleeping problems, I am now sticking to a certain course in my life. 5. Keeping my sleeping problems under control takes first priority. 6. I need to concentrate on getting rid of my sleeping problems. 7. It’s important to keep on fighting these sleeping problems. 8. My thoughts and feelings about my sleeping problems must change before I can take important steps in my life. Scoring Activities Engagement: Sum items 1, 2, 3, 4. Willingness: Reverse score items 5, 6, 7, 8, and sum. Total: Activity Engagement + Willingness. High scores equals high level of acceptance.
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http://dx.doi.org/10.5665/sleep.5170
DEVELOPMENT OF THE SLEEP PROBLEM ACCEPTANCE QUESTIONNAIRE
Measuring Acceptance of Sleep Difficulties: The Development of the Sleep Problem Acceptance Questionnaire Kristoffer Bothelius, MSc1; Susanna Jernelöv, PhD2; Mats Fredrikson, PhD1; Lance M. McCracken, PhD3; Viktor Kaldo, PhD2 Department of Psychology, Uppsala University, Uppsala, Sweden; 2Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; Health Psychology Section, Psychology Department, Institute of Psychiatry, King’s College London, London, UK
1 3
Study Objectives: Acceptance may be an important therapeutic process in sleep medicine, but valid psychometric instruments measuring acceptance related to sleep difficulties are lacking. The purpose of this study was to develop a measure of acceptance in insomnia, and to examine its factor structure as well as construct validity. Design: In a cross-sectional design, a principal component analysis for item reduction was conducted on a first sample (A) and a confirmatory factor analysis on a second sample (B). Construct validity was tested on a combined sample (C). Setting: Questionnaire items were derived from a measure of acceptance in chronic pain, and data were gathered through screening or available from pretreatment assessments in four insomnia treatment trials, administered online, via bibliotherapy and in primary care. Participants: Adults with insomnia: 372 in sample A and 215 in sample B. Sample C (n = 820) included sample A and B with another 233 participants added. Measures: Construct validity was assessed through relations with established acceptance and sleep scales. Results: The principal component analysis presented a two-factor solution with eight items, explaining 65.9% of the total variance. The confirmatory factor analysis supported the solution. Acceptance of sleep problems was more closely related to subjective symptoms and consequences of insomnia than to diary description of sleep, or to acceptance of general private events. Conclusions: The Sleep Problem Acceptance Questionnaire (SPAQ), containing the subscales “Activity Engagement” and “Willingness”, is a valid tool to assess acceptance of insomnia. Keywords: acceptance, experiential avoidance, insomnia, principal component analysis, psychometric evaluation, scale construction, Sleep Problem Acceptance Questionnaire, willingness Citation: Bothelius K, Jernelöv S, Fredrikson M, McCracken LM, Kaldo V. Measuring acceptance of sleep difficulties: the development of the sleep problem acceptance questionnaire. SLEEP 2015;38(11):1815–1822.
INTRODUCTION The concept of acceptance, the capacity to make an active choice to be more open toward psychological experiences,1 has gained popularity and scientific support within behavioral medicine.2 Acceptance has been most extensively studied in relation to chronic pain,3,4 but also in diabetes,5 epilepsy,6,7 fatigue,8,9 smoking cessation,10,11 stuttering,12 and tinnitus,13,14 among other conditions. In behavioral medicine, acceptance has been shown to be a key therapeutic process mediating the effect of treatment methods on outcome, for example, in the treatment of chronic pain15,16 and tinnitus.17 Identifying mediators of change may improve understanding of the nature of health problems as well as enhance treatment effects.18 An area where acceptance may also be relevant, but has not yet been systematically investigated, is the area of insomnia or sleep problems more generally.19–22 Acceptance is an important target for the therapeutic process in acceptance-based treatments. Acceptance and avoidance are counterparts, where “experiential avoidance” in particular, is defined as attempts to control or limit contact with distressing thoughts, feelings or other aversive internal
Submitted for publication December, 2014 Submitted in final revised form April, 2015 Accepted for publication May, 2015 Address correspondence to: Kristoffer Bothelius, MSc, Department of Psychology, Uppsala University, Box 1225, 751 42 Uppsala, Sweden; Tel: +46 70 398 12 13; Fax: +46 18 50 35 39; Email: kristoffer.bothelius@ psyk.uu.se SLEEP, Vol. 38, No. 11, 2015
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experiences. Such avoidance reduces discomfort momentarily, but may lead to long-term negative consequences.23 Preventing experiential avoidance and facilitating experiential exposure, including emotional exposure, seems to be one of the fundamental therapeutic components within a range of empirically supported psychological treatments.24 Within an acceptancebased framework, the pathological process that drives insomnia could be described as beginning with the unpleasant experience of being awake at night when one wants to be sleeping, and being tired in the daytime when one wants to be energetic.25 To avoid these experiences one may then adopt a number of behavior patterns, such as spending excessive time in bed trying to sleep, daytime napping, or other patterns that constitute an irregular sleep-wake schedule.26 Unfortunately, these behavior patterns interfere with homeostatic and circadian mechanisms, and can result in a conditioned arousal in the bed and bedroom, which maintains sleep problems.27 Thus, attempts to avoid disturbing experiences related to insomnia can paradoxically feed the insomnia itself. An alternate behavior pattern would be to be open and accepting of the experiences of insomnia, which can certainly stop the struggling to fall asleep, and possibly improve sleep. In order to address the possible role of acceptance in relation to insomnia, a measure of acceptance of sleep problems, such as insomnia, is needed. General tools for measuring acceptance have been developed, for example, the Acceptance and Action QuestionnaireII.28 However, specific instruments are often more responsive to change than generic instruments,29 and may better reflect processes conceptualized in relation to a specific problem area. In addition, it has been recommended that such instruments The Sleep Problem Acceptance Questionnaire—Bothelius et al.
should be as short as possible, to minimize the burden on respondents.30–32 There is an example of a well-developed specifically focused instrument for measuring acceptance in chronic pain, the 20-item Chronic Pain Acceptance Questionnaire (CPAQ). It was originally based on a pool of 34 items.33 The questionnaire is now extensively studied34 and shown to have a two-factor structure assessing Activity Engagement (i.e., engaging in activities in the presence of pain) and Pain Willingness (i.e., refraining from attempts to control or reduce pain).35 The questionnaire has been adapted for use with tinnitus and fatigue, and these adaptations have kept a similar two-factor structure.36,37 For studying acceptance in insomnia, we aimed to develop a new assessment instrument that we now refer to as the Sleep Problem Acceptance Questionnaire (SPAQ). The goal for this measure was to gain the ability to examine the role of acceptance in relation to variables that reflect quality of sleep, and also to determine whether acceptance could be a treatment process variable. It was deemed desirable that the questionnaire resemble similar acceptance questionnaires used successfully in other behavioral medicine contexts. The purpose of the current study was to investigate the item content and factor structure, internal consistency, and construct validity of the SPAQ. We predicted that the results would reflect a two-factor structure found in subjects with chronic pain, tinnitus, and fatigue as previously described, and this is also in line with central constructs in acceptancebased theory: “willingness” (i.e., being fully in contact with the present moment) and “committed action” (i.e., persisting with or changing behavior in the pursuit of goals and values).1 Because acceptance of tinnitus mediates the effect of subjective tinnitus loudness on tinnitus distress,38 and acceptance of chronic pain mediates the effect of pain severity on pain interference,39 we predicted that acceptance of sleep problems would more closely relate to the subjective experience of the disturbance than to descriptive aspects of sleep (such as sleep onset latency and wake time after sleep onset). It was hypothesized that the SPAQ should correlate positively with other measures of acceptance and negatively with subjective insomnia severity. It was also hypothesized that the SPAQ would be negatively correlated with sleep onset latency and wake time after sleep onset. METHODS Design A principal component analysis (PCA) was conducted on a first sample (A) to reduce the number of items, and this was followed by a confirmatory factor analysis on a second sample (B). Construct validity was assessed on a combined sample (C) through regression analyses and correlations with established measures of acceptance, insomnia, and other sleep related factors. Participants Sample A consisted of screening assessments of 372 subjects applying for two studies of Internet-delivered cognitive behavioral therapy for insomnia,40,41 72% women, mean age 42.0 (standard deviation [SD] = 15.0). Education level: compulsory school 5.5%, upper secondary school 26.6%, and SLEEP, Vol. 38, No. 11, 2015
college/university 67.9%. The study protocol was approved by the regional ethical review board in Stockholm (Diary No. 2009/1810-31/3), and is registered at ClinicalTrials.gov, registration ID: NCT01256099. Sample A+ includes these 372 participants, and an additional 233 who were screened after the PCA had already been performed, resulting in 605 participants. In sample B (total n = 215) subjects from two trials were merged: (I) Pretreatment assessments of 156 media recruited adults with primary or comorbid insomnia participating in a bibliotherapy study,42 75% women, mean age 50.8 (SD = 11.8). Education level: compulsory school 4.5%, upper secondary school 29.5%, and college/university 65.9%. The study protocol was approved by the regional ethical review board in Stockholm (Diary No. 2008/23-31/4), and is registered at ClinicalTrials. gov, registration ID: NCT01105052. (II) Pretreatment assessment of 59 adults with primary or comorbid insomnia participating in a randomized controlled study of manual-guided cognitive behavior therapy for insomnia, delivered by ordinary primary care personnel in general medical practice,43 90% women, mean age 50.7 (SD = 11.7). Education level: compulsory school 27.6%, upper secondary school 51.7%, and college/university 20.7%. The study protocol was approved by the regional ethical review board in Uppsala (Diary No. 2008/080), and is registered at ClinicalTrials. gov, registration ID: NCT01655797. There was no statistically significant difference in age between sample A (mean = 47.0, SD = 15.0) and sample B (mean = 48.2, SD = 13.4), t(489.9) = 1.00, P = 0.32, nor sex, χ2(1, n = 587) = 3.19, P = 0.07, but education level was higher in sample A, χ2(2, n = 575) = 33.66, P < 0.001. Subjects from sample A+ were merged with subjects in sample B, forming sample C, composed of 820 subjects. All subjects were screened for other common untreated sleep disorders in diagnostic interviews. Measures Instrument Development
The first two authors (KB and SJ) reviewed the 34 original items behind the CPAQ, derived from Geiser,44 together with a sleep expert (Jan-Erik Broman, PhD). Despite the fact that all 34 items have not been used in any established version of the CPAQ, they were considered to have potential relevance for insomnia and were included in the initial principal components analysis. KB and SJ then translated all items to Swedish and adapted them to insomnia. The items were backtranslated into English and one of the authors (LM) then approved the backtranslation from theoretical as well as semantic aspects. The adaption was quite straightforward; most of the time by simply exchanging “pain” with “sleeping problems”. This formulation is in line with other measures of insomnia, for example, the widely known Insomnia Severity Index.45 For example, the item reading “although things have changed, I am living a normal life despite my chronic pain” was changed to “although things have changed, I am living a normal life despite my sleeping problems.” Like the CPAQ, each item is rated on a 0- to 6-response scale. For the SPAQ, 0 equals “disagree” and 6 equals “completely agree.” Items for which a
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high score implicates low acceptance are reversed in all statistical evaluations so that a high total score reflects a high level of acceptance. Because our objective was a short questionnaire free from items with unclear wording, we wanted to reduce the number of items in an initial principal components analysis.
number of items per scale dimension,53,54 with at least four items in each subscale.55 The item reduction was performed stepwise, starting with excluding the items with the lowest factor loading. Items with low standard deviations, double loadings, or that were considered theoretically ambiguous were also removed.
Additional Measures
Confirmatory Factor Analysis
Acceptance and Action Questionnaire-II: The Acceptance and Action Questionnaire-II (AAQ-II)28 is a seven-item scale mostly focused on general psychological acceptance of private events. All of the items are negatively keyed, so it is sometimes referred to as a measure of experiential avoidance. In the current study lower scores indicate higher acceptance. Insomnia Severity Index: The Insomnia Severity Index (ISI)45 is a widely used, reliable, and valid46 seven-item selfreport measure for insomnia, targeting subjective symptoms, consequences of insomnia, and distress. A high total score indicates a high level of perceived sleep difficulties. Dysfunctional Beliefs and Attitudes about Sleep Scale: The Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS)47 is a 30-item self-report questionnaire evaluating sleep-disruptive cognitions. A higher score indicates more unhelpful cognitions. Sleep-Related Behaviours Questionnaire: The 32-item Sleep-Related Behaviours Questionnaire (SRBQ)48 is designed to assess the use of safety behaviors in insomnia (i.e., strategies aiming to prevent a feared outcome, which may in fact be contributing to the maintenance of the disorder). A higher score indicates more safety behaviors. Sleep Diary: Sleep diaries are routinely included in insomnia research. Despite an earlier lack of standardization,49 sleep diaries yield reliable quantification of sleep parameters and are generally recommended for quantitative sleep assessment in insomnia research.50 Sleep diaries give information about the night-to-night variability in sleep timing (bedtimes and rise times), actual time slept (total sleep time, TST), how many minutes it takes to fall asleep (sleep onset latency, SOL), time spent awake during the night (wake time after sleep onset, WASO), and percentage of time in bed spent asleep (sleep efficiency, SE). Analyses The 34 originally adapted items (called SPAQ-34) were included in screening or pretreatment measures in the three insomnia studies in Sweden previously described. Principal Component Analysis
Item reduction was performed using an initial PCA with oblique rotation (direct oblimin), starting with all 34 items on sample A (n = 372). A wide range of recommendations regarding sample size in factor analysis has been proposed. Although there is a lack of agreement regarding rules of thumb, Comrey’s guide suggesting a minimum of 300 subjects51 and Nunnally’s heuristic of a subject to item ratio of 10:152 are often cited. Both of these criteria were met. Because we expected a two-factor solution, we restrained the number of factors to two. We wanted a short questionnaire but still followed the recommendations that measures have an equal SLEEP, Vol. 38, No. 11, 2015
To confirm the factors suggested by the PCA, structural equation modeling (SEM) was used to perform a confirmatory factor analysis (CFA) using sample B, n = 215. There is no simple rule regarding minimum sample size in a CFA, but having at least 200 subjects is advised.56 The AMOS software package (version 22.0)57 was used for the CFA. To complement the basic Chi-2 model fit test (testing if there is a difference between the model and the data), which is known for being very conservative except for small sample sizes, the following model fit indices and cutoff values were used: root mean square error of approximation (RMSEA < 0.08), comparative fit index (CFI > 0.95), standardized root mean square residual (SRMR < 0.09), and the Chi-2 value divided by the degrees of freedom (Chi-2/df < 3).58–61 Construct Validity
Construct validity was assessed by examining the relations with variables known to be theoretically linked with acceptance of insomnia. In these analyses, sample A+ was merged with sample B forming sample C, amounting to 820 subjects. To maximize power, missing data were excluded pairwise. The Kolmogorov-Smirnov test showed data on SOL, WASO, and SE derived from sleep diaries to be significantly different from a normal distribution. This sleep diary data were therefore logarithmically transformed, which normalized distribution, before correlations were computed. To analyze the unique contribution of the SPAQ on insomnia, a multiple regression was performed, with ISI score as an outcome variable and the SRBQ, the DBAS, and the SPAQ as predictors. RESULTS Principal Component Analysis The principal component analysis was performed on sample A. The reduction of items was performed in two steps and a final solution with two four-item factors was presented. The scree plot and the criterion of an eigenvalue above 1 supported this solution, and the theoretical and statistical adequacy of the items in each factor were inspected and found satisfactory. Thus, the solution presented in Table 1 was chosen. The content of the two subscales was deemed to be well in line with the corresponding subscales in the original CPAQ and hence similar labeling of the subscales was used, i.e., “Activity Engagement” and “Willingness”. The Kaiser–Meyer–Olkin Measure of Sampling Adequacy was found to be 0.83, which is considered good.62 The solution explained 65.9% of the total variance among all eight items. The Cronbach α of the two four-item subscales, 0.89 for Activity Engagement and 0.73 for Willingness, were deemed satisfactory.63 The Cronbach α for the scale as a whole was lower, 0.55. The correlation between the two subscales was r = 0.22.
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Table 1—Rotated factor loadings for the exploratory two-factor solution. Item 1 2 3 4 5 6 7 8
Content summary Although things have changed, I am living a normal life despite my sleeping problems. I lead a full life even though I have sleeping problems. My life is going well, even though I have sleeping problems. Despite the sleeping problems, I am now sticking to a certain course in my life. Keeping my sleeping problems under control takes first priority. I need to concentrate on getting rid of my sleeping problems. It’s important to keep on fighting these sleeping problems. My thoughts and feelings about my sleeping problems must change before I can take important steps in my life.
Factor 1 0.88 0.87 0.84 0.84 −0.16 −0.061 0.17 −0.18
Factor 2 −0.056 −0.003 −0.076 −0.003 0.78 0.79 0.77 0.61
n = 372.
Table 2—Correlations between the Sleep Problem Acceptance Questionnaire (SPAQ) subscales (Activity Engagement and Willingness), the total SPAQ score, and the Insomnia Severity Index (ISI), sleep onset latency (SOL), wake time after sleep onset (WASO), total sleep time (TST), sleep efficacy (SE), the Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS), and the Sleep-Related Behaviours Questionnaire (SRBQ).
Activity Engagement Willingness Total SPAQ-score a
ISI (n = 815) −0.449 b −0.450 b −0.563 b
AAQ II (n = 599) −0.382 b −0.193 b −0.368 b
SOL (n = 377) −0.139 a −0.078 −0.149 a
WASO (n = 187) −0.122 −0.245 a −0.223 a
TST (n = 377) −0.039 0.080 0.082
SE (n = 375) 0.087 0.050 −0.091
DBAS (n = 195) −0.397 b −0.410 b −0.514 b
SRBQ (n = 195) −0.534 b −0.373 b −0.594 b
P < 0.01. b P < 0.001.
was significant (χ2(19) = 45.8, P = 0.001), but this is very common for large sample CFAs.64 Overall, the support for the model was seen as sufficient considering that all other indicators were deemed strong or satisfactory, and we decided to let the initial model also be the final model presented in Figure 1. The Cronbach α for the whole measure was 0.59.
Figure 1—Structural equation model for the Confirmatory Factor Analysis for the final version of the Sleep Problem Acceptance Questionnaire.
Confirmatory Factor Analysis The initial model with two factors was tested on sample B in a confirmatory factor analysis. The SRMR (0.063), the CFI (0.96), and the Chi-2/df (2.4) indicated adequate fit. The RMSEA (0.081) was just above the threshold. The Chi-2 test SLEEP, Vol. 38, No. 11, 2015
Construct Validity For assessing construct validity, the newly developed SPAQ was correlated against existing measures of insomnia and acceptance related constructs, see Table 2. The SPAQ correlated negatively with the ISI and the AAQII. In the AAQ-II lower scores indicate higher acceptance so this correlation is actually positive. The AAQ-II also correlated with the ISI, but to a lesser extent, r = 0.237, P < 0.001. The SPAQ correlated negatively with WASO and SOL derived from sleep diaries (but not with TST or SE), the DBAS, and the SRBQ. The Activity Engagement subscale correlated negatively with SOL and the Willingness subscale correlated negatively with WASO. Both subscales correlated negatively with the ISI, the AAQ-II, the DBAS, and the SRBQ. A multiple regression (forced entry in two steps) showed that in step 1, both the SRBQ and DBAS significantly predicted ISI score and together they predicted 17% of the variance. When the SPAQ was added in the second step, the total predicted variance increased significantly (P < 0.001) by another 15% and only the SPAQ remained a significant predictor (Table 3). We therefore re-performed these analyses, but separately adding the two subscales of SPAQ to the SRBQ and the DBAS. When “Willingness” was added in the second step (B = −0.20, P = 0.001), the SRBQ remained significant (B = 0.05, P = 0.03), but not the DBAS. When the “Activity Engagement” subscale was added 1818
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instead in step 2 (B = −0.24, P < 0.001) the DBAS was still significant (B = 0.02, P = 0.02), but not the SRBQ. In sample A+ mean value for the total SPAQ score was 20.23 (SD = 8.37), for the Activity Engagement subscale 11.97 (SD = 5.77), and for the Willingness subscale 8.25 (SD = 4.66). In the bibliotherapy study mean value for the total SPAQ was 17.16 (SD = 8.09), for the Activity Engagement subscale 9.26 (SD = 5.46), and for the Willingness subscale 7.90 (SD = 4.96). In the primary care study mean value for the total SPAQ was 18.47 (SD = 9.11), for the Activity Engagement subscale 12.03 (SD = 5.70), and for the Willingness subscale 6.44 (SD = 5.21). DISCUSSION The aim was to develop and validate a brief measure of acceptance of sleep problems. This resulted in the SPAQ, an eight-item questionnaire with two factors, Willingness and Activity Engagement. To our knowledge, this is the first specific measure of acceptance in insomnia. This structure is in agreement with two-factor solutions found for similar acceptance questionnaires used in chronic pain, tinnitus, and fatigue, and our labeling of the subscales as Activity Engagement and Willingness was in line with these other measures. An analysis of construct validity shows that the SPAQ has a strong negative correlation with the ISI, but only a weak negative correlation with SOL and WASO, and no correlation with SE or TST. This is somewhat in line with what was predicted; low acceptance of insomnia is more closely related to subjective effect of severe sleeping problems, than to more descriptive aspects of the sleep (e.g., long time awake during the night and short sleep length). The negative correlation between the SPAQ and the negatively keyed AAQ-II (in fact a positive correlation) was medium sized, whereas the correlation between the AAQ-II and the ISI was small. The insomnia-specific measure of acceptance, SPAQ, hence seems to correlate fairly well to the more general acceptance questionnaire AAQII, while at the same time correlating more closely with the subjective symptoms and consequences of insomnia than the AAQ-II manages to do. A negative correlation with the AAQII is expected because this measure is theoretically reversed and reflects avoidance. The SPAQ correlates highly negatively with both the DBAS and the SRBQ, indicating that lower acceptance of insomnia is closely related to more sleep-disruptive beliefs, attitudes, and safety behaviors. As shown in the multiple regression analysis, the SPAQ reflects a unique concept that may be of importance for understanding perceived insomnia severity and for guiding psychological treatment for insomnia. Activity Engagement means persistence with normal activities, even when sleep is perceived as not being satisfying, whereas Willingness reflects refraining from attempts to fight sleep problems and control sleep. These scales mirror the central theoretical construct in acceptance-based therapies: “psychological flexibility.” This construct, in turn, reflects the ability to experience the current moment without trying to change it and to engage in personally important activities; again, both when it is easy to do this but particularly when one encounters potential barriers such as unwanted or discouraging thoughts and feelings.1 In insomnia this could be SLEEP, Vol. 38, No. 11, 2015
Table 3—Multiple regression with the Insomnia Severity Index as outcome variable, the Dysfunctional Beliefs and Attitudes about Sleep and the Sleep-Related Behaviours Questionnaire as predictors in step 1, and the Sleep Problem Acceptance Questionnaire added in step 2. Step 1 Constant DBAS SRBQ
B
SE B
β
9.21 0.03 0.06
1.42 0.01 0.02
0.22a 0.23a
Step 2 Constant DBAS SRBQ SPAQ
20.37 0.01 0.00 −0.22
2.13 0.01 0.02 0.03
0.11 (ns) 0.00 (ns) −0.50b
R 2 = 0.17 for Step 1, ΔR2 = 0.15 for Step 2 (P < 0.001). aP < 0.01. b P < 0.001. DBAS, Dysfunctional Beliefs and Attitudes about Sleep; ns, not significant; SRBQ, Sleep-Related Behaviours Questionnaire; SPAQ, Sleep Problem Acceptance Questionnaire.
translated to willingness to experience nonoptimal sleep, and to direct energy toward personally important goals despite resistance, instead of fighting or trying to control insomnia. An instrument to assess acceptance, and it subcomponents, in insomnia is necessary to examine the relations between acceptance, suffering, and treatment outcome. The results suggest that these two subscales represent a whole process and both ought to be included when one is interested in acceptance in insomnia. Acceptance is an active choice. In other behavioral medicine disciplines there is accumulating evidence that pursuing valued activities may be a more successful approach to chronic diseases, as opposed to fighting against or trying to avoid unpleasant symptoms.2 Although fighting or avoiding unwanted experiences might result in temporary relief from these symptoms, this form of experiential avoidance may result in increased interference with life in the long run. In chronic pain research there are data showing that low acceptance is correlated with both high psychological distress and high physical disability,65–67 and in chronic fatigue low acceptance has been shown to relate to high psychological distress9 and to predict low physical functioning.8 The role of acceptance in insomnia could be, as with diabetes,5 both an important mediator of change, and a desired outcome following treatment. From a purely theoretical standpoint however, acceptance is never the ultimate goal—only a way to approach life in tune with one’s values.1 Likewise, symptom reduction is not an end goal of acceptance-based treatment, but such treatment has nonetheless been shown to reduce the number of epileptic seizures6,7 and reduce overall frequency of stuttering,12 showing that acceptance is not merely an inert response to symptoms, or passive resignation. One possible difference between acceptance in insomnia and acceptance in, for example, chronic pain and tinnitus is in the willingness factor. In tinnitus and chronic pain this factor seems to be characterized by control and avoidance, whereas in insomnia there is more of control and fight. One item that is unique for the SPAQ is: “It’s important to keep
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on fighting these sleeping problems,” and in contrast with the CPAQ and the Tinnitus Acceptance Questionnaire (TAQ)36 items do not include conventional avoidance behavior patterns. One could speculate there might be different qualities in the acceptance behaviors that are most typical for different underlying conditions. For example, passive avoidance and withdrawal may relate more to depressive behavior problems in chronic pain and tinnitus, and require greater behavioral activation as a therapeutic response,68 whereas a more actionoriented fighting style of avoidance in insomnia may lend itself to problems with states of hyperarousal69 and a dysregulated stress system,70 thus requiring different therapeutic methods that reduce the effect of thoughts and feelings on behavior. It is worth emphasizing the potential value of an assessment instrument that can provide reliable and valid data regarding acceptance of insomnia. Currently, in most areas of cognitive behavioral therapy, there is an increased interest in therapeutic process, or active mechanisms of treatment effect. Aspects of psychological flexibility, such as acceptance, appear to hold great potential as process variables that can help us to better select, target, and optimize methods for addressing problems such as sleep disturbance and insomnia.4 The study has some limitations that deserve mention. The four-plus-four-item version that the authors advocate is based on statistical considerations, as well as a theoretical discussion of balancing two important constructs. Because the questionnaire contains two different factors, the Cronbach α for the whole scale is low, and it is important to consider the subscales separately when interpreting the scores.71 The study did not assess the test-retest reliability of the measure or its sensitivity to change, and it did not produce clinically relevant cut-off scores that allowed for individual scores to be classified as high or low. Even if the SPAQ shows significant correlations with other insomnia specific measures, these correlations cannot support conclusions regarding causality, and it is possible that the relations are bidirectional. Finally, all subjects had a verified insomnia diagnosis and were seeking treatment. It is possible that a population not seeking treatment or with subthreshold insomnia may have responded differently. A merit of the study is that the factor structure is validated on a separate sample. Future studies might assess the prognostic value of SPAQ scores for different insomnia treatments and explore whether acceptance of sleep problems can explain some of the differences between descriptive sleep measures and subjective insomnia severity, in line with how tinnitus-specific acceptance partially mediates the relation between subjective tinnitus loudness and tinnitus distress,38 and how pain-specific acceptance partially mediates the relation between pain severity and pain interference.39 To conclude, the SPAQ seems to be a theoretically adequate and statistically sound measure of acceptance in people with insomnia. In future use of the SPAQ, one should consider not only the total score, but also the two subscales. Although insomnia was meant to be the main target of this questionnaire, and represents the primary problem within the samples for which the measure has been developed, the uses of generic sleep concepts in the questionnaire enable studies of acceptance in populations with sleep disturbances other than insomnia. SLEEP, Vol. 38, No. 11, 2015
ACKNOWLEDGMENTS The authors thank Ingrid Andrén, Kerstin Blom, Martin Kraepelien, Kicki Kyhle, Brjánn Ljótsson, Sara Rydh, and Sofi Sjöholm-Jenssen for help with data collection, Sandra Bates for help with the back translation, Sheri Fox for proofreading, and Jan-Erik Broman for help with the development of the SPAQ and valuable comments on the manuscript. DISCLOSURE STATEMENT This was not an industry supported study. Dr. Jernelöv is the author of a commercially available self-help book used in three of the randomized trials from which data were collected. The other authors have indicated no financial conflicts of interest. The work was performed at the Department of Psychology, Uppsala University, Uppsala, and the Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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APPENDIX Sleep Problem Acceptance Questionnaire Directions: Below you will find a list of statements. Please rate how much you agree with each statement by marking one alternative. Use the rating scale below to make your choices. 0
1
2
3
4
5
6
Disagree
Almost completely disagree
Slightly agree
Partly agree
Moderately agree
Almost completely agree
Completely agree
1. Although things have changed, I am living a normal life despite my sleeping problems. 2. I lead a full life even though I have sleeping problems. 3. My life is going well, even though I have sleeping problems. 4. Despite the sleeping problems, I am now sticking to a certain course in my life. 5. Keeping my sleeping problems under control takes first priority. 6. I need to concentrate on getting rid of my sleeping problems. 7. It’s important to keep on fighting these sleeping problems. 8. My thoughts and feelings about my sleeping problems must change before I can take important steps in my life. Scoring Activities Engagement: Sum items 1, 2, 3, 4. Willingness: Reverse score items 5, 6, 7, 8, and sum. Total: Activity Engagement + Willingness. High scores equals high level of acceptance.
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