Predictors of poor sleep quality and excessive daytime sleepiness in Turkish adults with type 2 diabetes € Belg€ uzar Kara and Ozge Kılıcß Accepted for publication: 10 September 2014
Aim To determine the prevalence of poor sleep quality and excessive daytime sleepiness in Turkish patients with type 2 diabetes and identify the effects of demographic/diseaserelated characteristics and physical activity on poor sleep quality and excessive daytime sleepiness.
Background Recent studies have demonstrated that sleep quantity and quality are associated with metabolic changes that may lead to cardiovascular diseases, insulin resistance, impaired glucose tolerance and type 2 diabetes. These results suggest that sleep problems in patients with type 2 diabetes may have serious consequences. However, studies on sleep quality and daytime sleepiness risk factors in this population are limited and have reported inconsistent results (Chasens et al. 2013, Song et al. 2013). The effects of income level, the caregiver’s presence and physical activity are also not clear.
Design and sample We conducted a cross-sectional study between November 2013 and February 2014. A total of 250 patients with type 2 diabetes followed by a diabetes outpatient clinic in a large Turkish city were enrolled. Inclusion criteria were age ≥18 years, type 2 diabetes diagnosis for at least one month, ability to communicate in Turkish and agreeing to particiAuthors: Belg€ uzar Kara, RN, Associate Professor, Instructor, Department of Internal Medicine Nursing, School of Nursing, € Gulhane Military Medical Academy, Ankara; Ozge Kılıcß, RN, Nurse, Department of Endocrinology and Metabolism Diseases, Gulhane Military Medical Academy, Ankara, Turkey
What does this paper contribute to the wider global clinical community?
• The results of this study suggest that poor sleep qual•
ity and excessive daytime sleepiness are prevalent among patients with type 2 diabetes. Having no caregiver, poor self-rated health and a moderate or inadequate family income are associated with poor sleep quality and this in return is associated with excessive daytime sleepiness. This paper highlights the importance of implementing effective interventions by taking into account the factors contributing to poor sleep quality and excessive daytime sleepiness in patients with type 2 diabetes.
pate in the study. Exclusion criteria were a severe comorbid condition, major psychiatric disorder, cognitive impairment, sleep disorders, alcoholism, pregnancy, lactation, clinical instability and working in the night shift. One hundredeighty patients (594% female) met the inclusion criteria. This study was approved by the Hospital’s Local Ethics Committee. Written informed consent was obtained from all participants.
Methods A self-administered questionnaire was used to collect data on participants’ characteristics. A five-point Likert scale (self-rated health; SRH) ranging from ‘very poor’ to ‘very good’ was used for measuring perceived health status. The Correspondence: Belg€ uzar Kara, Associate Professor, Instructor, G€ ulhane Askeri Tıp Akademisi, Hemsßirelik Y€ uksekokulu, 06013 Ankara, Turkey. Telephone: +90 312 3041565. E-mail: [email protected] This manuscript was presented as a poster presentation at the 50th National Diabetes Congress, Antalya, Turkey, April 23–27, 2014.
Research in Brief
SRH was classified into ‘poor’ (fair/poor/very poor) and ‘good’ health (good/very good). The sleep quality was assessed using the Turkish version of the Pittsburgh Sleep Quality Index (PSQI). The PSQI consists of 24 items. It is a four-point Likert scale ranging from 0 (not at all) to 3 (three or more times a week). The PSQI generates a global score (≥5 poor sleep quality; range = 0–21) and seven component scores (Agarg€ un et al. 1996). The Turkish version of the Epworth Sleepiness Scale (ESS) was used to measure excessive daytime sleepiness. It is an eight-item, four-point Likert scale (0 = never, 3 = always). The ESS yields a total score (≥10 excessive daytime sleepiness; range = 0–24) (Agarg€ un et al. 1999). The Cronbach’s alpha coefficients of the global PSQI and the ESS were high in the current study (075 and 088; respectively). The Turkish short version of the International Physical Activity Questionnaire (IPAQ-S) was used to measure physical activity. The metabolic equivalent of task (MET)minutes per week was calculated (duration 9 frequency 9 MET intensity). The intensity of physical activity was classified as low (<600 MET-min/week), moderate (600–3000 MET-min/week) or high (>3000 MET-min/ week) (Saglam et al. 2010). All statistical analyses were performed using the SPSS for Windows statistical software (version 15.0; SPSS Inc., Chicago, IL, USA). Descriptive statistics and reliability analyses were conducted. Univariate and multivariate logistic regression analyses with backward elimination were performed to determine independent risk factors associated with outcome variables. Variables with p values <020 in the univariate analysis were used for multivariate models. The categorical variables selected for the multivariate analysis of poor sleep quality included marital status, education level, employment status, perceived income level, the presence of a caregiver and SRH, and the continuous variables were body mass index (BMI) and waist circumference. The same variables for daytime sleepiness were marital status, the SRH and the global PSQI score, and the BMI, waist circumference, fasting plasma glucose, postprandial plasma glucose (PPG) and glycosylated hemoglobin, respectively. A p value of <005 was regarded as statistically significant.
Results Table 1 presents descriptive statistics of the participants’ characteristics and the scale scores. Poor sleep quality and excessive daytime sleepiness were found in 633 and 217% of the patients, respectively. Most patients
reported low (611%) or moderate (344%) levels of physical activity. The multivariate logistic regression analysis showed that the presence of a caregiver [adjusted Odds Ratio (OR):044; 95% confidence interval (CI):022–091, p = 0028] and good SRH (OR:043; 95%CI:020–095, p = 0036) were protective factors against poor sleep quality. A moderate or inadequate family income (compared to adequate income) was associated with increased odds of poor sleep quality (OR:217; 95%CI:104–452, p = 0038 and OR:419; 95%CI:120–1471, p = 0025; respectively). Higher waist circumference was also significantly associated with poor sleep quality (p = 0008), but the OR value very close to 1 indicated no influence (OR:103; 95% CI:101–106). Poor sleep quality (OR:418; 95%CI:151–1160, p = 0006), higher levels of BMI (OR:109; 95%CI:102– 116, p = 0010) and PPG (OR:101; 95%CI:100–101, p = 0006) were associated with increased likelihood of excessive daytime sleepiness. However, the ORs for BMI and PPG were again very close to 1. The IPAQ-S score was
Table 1 Descriptive statistics of participants’ characteristics and the scale scores Variables
Age (years) Disease duration (months) Body mass index (kg/m2) Waist circumference (cm) Fasting plasma glucose (mg/dl) Postprandial plasma glucose (mg/dl) Glycosylated hemoglobin (%) Global PSQI Subjective sleep quality Sleep latency Sleep duration Habitual sleep efficiency Sleep disturbance Use of sleep medication Daytime dysfunction ESS IPAQ-S (MET-min/week)
not associated with poor sleep quality and excessive daytime sleepiness (p > 005).
Conclusions Poor sleep quality and excessive daytime sleepiness were prevalent among patients with type 2 diabetes as reported in previous studies (Chasens et al. 2013, Song et al. 2013). Many patients with type 2 diabetes were not sufficiently active. Patients who took care of themselves, those with poor SRH and patients who had financial difficulties were more likely to have poor sleep quality. We do not know how financial status affects sleep quality. However, it is possible that individuals in financial difficulty are more exposed to adverse conditions and use ineffective coping strategies. The result would be decreased physical and mental health compromising sleep quality. On the other hand, poor sleep quality and poor health interact with each other and can cause low income (Moore et al. 2002). Further research is required to elucidate the causes of this association. Excessive daytime sleepiness was also more common among patients with poor sleep quality. Poor sleep quality and excessive daytime sleepiness were not influenced by physical activity. The limitations of this study include cross-sectional design, the relatively small sample size and the use of self-reported data on sleep patterns. The cross-sectional design limits inference on the cause and effect. Another limitation is that confounding factors that can influence sleep such as medications, diet and environment were not evaluated in this study. Therefore, the results of this study cannot be generalised to all Turkish patients with type 2 diabetes.
Relevance to clinical practice A better understanding of risk factors related to sleep quality and daytime sleepiness of patients with type 2 diabetes could facilitate effective interventions that improve health outcomes. Nurses should be aware of the factors that affect sleep quality and daytime sleepiness of patients and should provide information and counselling on sleep hygiene measures as well as psychosocial support.
Key words daytime sleepiness, nurses, nursing, sleep quality, type 2 diabetes
Acknowledgements The authors thank all the patients who took the time to participate in this study. Our thanks are also extended to Associate Professor Cengizhan Acßıkel, MD, for his advice on statistics.
Disclosure The authors have confirmed that all authors meet the ICMJE criteria for authorship credit (www.icmje.org/ethical_1author.html), as follows: (1) substantial contributions to conception and design of, or acquisition of data or analysis and interpretation of data, (2) drafting the article or revising it critically for important intellectual content, and (3) final approval of the version to be published.
Conflict of interest The authors declare no conflict of interest related to this article.
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Saglam M, Arikan H, Savci S, Inal-Ince D, Bosnak-Guclu M, Karabulut E & Tokgozoglu L (2010) International Physical Activity Questionnaire: reliability and validity of the Turkish version. Perceptual and Motor Skills 111, 278–284. Song Y, Ye X, Ye L, Li B, Wang L & Hua Y (2013) Disturbed subjective sleep in Chinese females with type 2 diabetes on insulin therapy. PLoS ONE 8, e54951.
Research in Brief
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