International Journal of Psychophysiology 94 (2014) 351–357

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International Journal of Psychophysiology journal homepage: www.elsevier.com/locate/ijpsycho

Effects of menstrual cycle and neuroticism on females' emotion regulation Mengying Wu a,d, Renlai Zhou a,b,c,d,⁎, Yamei Huang a,d a

Beijing Key Lab of Applied Experimental Psychology, School of Psychology, Beijing Normal University, Beijing 100875, China State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China Department of Psychology, School of Social and Behavioral Sciences, Nanjing University, Nanjing 210023, China d Research Center of Emotion Regulation, Beijing Normal University, Beijing 100875, China b c

a r t i c l e

i n f o

Article history: Received 28 March 2014 Received in revised form 26 September 2014 Accepted 5 October 2014 Available online 13 October 2014 Keywords: Neuroticism Menstrual cycle Emotion regulation Reappraisal

a b s t r a c t Fifteen highly neurotic women and 21 women who were low in neuroticism participated in this study. The women were surveyed three times over a single menstrual cycle during the mid-late luteal, menstrual, and late follicular phases. Each time, the participants were asked to use reappraisal to regulate their emotions, which were evoked by a sad film clip, and their subjective emotional experiences and physiological responses were recorded. The results showed that neuroticism had no impact on emotion regulation, and the females experienced fluctuations in their emotion regulation success over their menstrual cycle. During the menstrual phase, women reported significantly higher levels of reappraisal, but subjective sadness did not differ throughout the three phases. Additionally, the regulation effects on galvanic skin response (GSR) were smaller during the menstrual phase than in the mid-late luteal phase. These results suggested that women in the menstrual phase expended more effort but gained less success at regulating their emotions. © 2014 Elsevier B.V. All rights reserved.

1. Introduction The menstrual cycle is a normal physical process that all women experience and is characterized by tightly orchestrated changes in the levels of ovarian estrogen and progesterone. Researchers have confirmed that diverse body systems (e.g., cardiovascular system, central nervous system, endocrine system, female reproductive system, and immune system) are replete with estrogen receptors and that progesterone also acts on numerous tissues. Therefore, cyclically fluctuating levels of estrogen and progesterone have a significant biological effect on the female body, one with both physical and emotional ramifications (for a review, see Farage et al., 2009). Because of the initiation and mediation roles that these two hormones play in the menstrual cycle, a menstrual cycle can be divided into three phases that are characterized by levels of these hormones. The menstrual phase starts with the onset of menstrual flow, lasts between four and six days, and is characterized by low levels of both progesterone and estrogen. The follicular phase typically begins on day 7 and ends on day 14. Estrogen levels rise rapidly in the late follicular phase (i.e., postmenstrual phase) and reach their peak one day before ovulation. The luteal phase is typically defined as ⁎ Corresponding author at: Department of Psychology, School of Social and Behavioral Sciences, Nanjing University, Nanjing 210023, China. Tel.: +86 025 89680960x418. E-mail address: [email protected] (R. Zhou).

http://dx.doi.org/10.1016/j.ijpsycho.2014.10.003 0167-8760/© 2014 Elsevier B.V. All rights reserved.

the period between days 15 and 28, during which there is a steady rise in progesterone levels that peak in the mid-luteal phase (i.e., premenstrual phase), in parallel with a second estrogen peak (for a review, see Farage et al., 2008). Surveys conducted with Chinese women have indicated that approximately 20% to 30% of participants experience physical and/or psychological discomfort during their premenstrual phase (i.e., luteal phase), as well as their menstrual phase, with the most common emotional symptoms being irritability and mood swings (Lee et al., 2009; Yu et al., 1996). According to a review of prospective data studies, a majority of studies (61.7%) have found that mood swings occur during the menstrual cycle (Romans et al., 2012). Researchers suggested that women's emotional responses to negative stimuli appear to be decreased by estrogen but enhanced by progesterone (for a review, see Sakaki and Mather, 2012). Consistent with this, studies that use negative emotional material as stimuli have found that compared to women's responses during the late follicular (high estrogen and low progesterone) phase, women's emotional responses are more intense during the menstrual (low estrogen and low progesterone) phase (Andreano and Cahill, 2010; Goldstein et al., 2005) or the late luteal (low estrogen and high progesterone) phase (Derntl et al., 2008; Gingnell et al., 2012; Ossewaarde et al., 2010). Some studies have implied that women's emotion regulation may also be influenced by the menstrual cycle. Researchers have studied

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the pattern of change regarding the resting frontal alpha asymmetry across the menstrual cycle and have found that left frontal activity is relatively higher in the menstrual phase than in the late follicular phase (Hwang et al., 2008). In a similar study, researchers used emotional faces as stimuli and found higher left frontal activity during the menstrual phase than in the late follicular phase when participants were presented with fearful faces (Hwang et al., 2009). Using functional magnetic resonance imaging in female subjects, researchers found that orbitofrontal cortex (OFC) activity for negative vs. neutral linguistic stimuli increased in the luteal phase and decreased in the follicular phase (Protopopescu et al., 2005). The regions of the left frontal cortex and OFC have most consistently been implicated in cognitive control processes, including emotion regulation (for a review, see Phillips et al., 2008). Thus, these brain imaging results indicate that the menstrual cycle may influence emotion regulation. However, the following question arises: Why do women have more intense emotional responses during the menstrual or luteal phases (Andreano and Cahill, 2010; Derntl et al., 2008; Gingnell et al., 2012; Goldstein et al., 2005; Ossewaarde et al., 2010), even though their activation of brain regions related to emotion regulation appear to be higher during these two phases (Hwang et al., 2008; Hwang et al., 2009; Protopopescu et al., 2005)? We believe that one possible explanation is that women do make more efforts to regulate negative emotions during the menstrual or luteal phases, but their efforts may not give them the expected return. To test this possibility, we need to investigate women's efforts and success at regulating their emotions in an emotion regulation paradigm. It should be noted that previous studies still have several limitations. First, researchers have not investigated women's emotional responding with respect to a task that calls for intentional emotion regulation. Second, previous lab studies compared women's emotional responses and brain activity to emotional stimuli during the menstrual (Andreano and Cahill, 2010; Goldstein et al., 2005; Hwang et al., 2009) or luteal phase to those during the follicular phase (Derntl et al., 2008; Gingnell et al., 2012; Ossewaarde et al., 2010; Protopopescu et al., 2005); however, they failed to find differences between the luteal and menstrual phases in terms of emotional responding. Third, previous studies have not focused on individual differences. Women's unique traits may play a role in determining their emotional responding during a menstrual cycle. For example, researchers have found that subjective experience and physiological responses towards negative emotion during a menstrual cycle are more influential for neurotic women than they are for women who are low in neuroticism (Wu et al., 2014). Furthermore, it has been observed that women who are high in neuroticism report having more premenstrual symptoms than women who are low in neuroticism do (Treloar et al., 2002; Van Den Akker et al., 1995). Generally, researchers consider neuroticism to be an influential factor regarding emotional experience; indeed, people high in neuroticism are particularly susceptible to negative mood inductions (Thake and Zelenski, 2013). However, the relationship between neuroticism and emotion regulation during a menstrual cycle requires further study. Based on the previous studies, the aim of the current study was to test the effects of the menstrual cycle and neuroticism on females' emotion regulation efforts and success. We investigated the emotional outcomes for highly neurotic women and women low in neuroticism when they were instructed to regulate induced negative emotions. All participants were tested three times, once during their mid-late luteal phase, once during menstrual phase and once during the late follicular phase. The specific emotion regulation strategy that we tested was cognitive reappraisal, which is defined as construing a potentially emotioneliciting situation in nonemotional terms. Experimental studies have observed reappraisal to be an effective strategy for decreasing negative emotional experience, physiological arousal and behavioral expression (for a review, see Gross, 2002). According to our previous findings, highly neurotic women's physiological responses (i.e., galvanic skin response, heart rate) are more likely to be affected by their menstrual

cycle than those of women low in neuroticism when watching sad film clips (Wu et al., 2014). Similarly, we used sad film clips as stimuli, and the mean amplitude of galvanic skin response (GSR) and heart rate (HR) were used as physiological arousal indices in the current study. GSR and HR were sensitive to sadness arousal (Kreibig et al, 2007; Kreibig, 2010; Troy et al., 2010; Wu et al., 2014), and they could be regulated by reappraisal, according to previous studies (Giuliani et al., 2008; Yuan et al., 2011). Emotion regulation success can be measured by the decrease of negative emotions and physiological arousal after cognitive reappraisal of negative stimuli (McRae et al., 2012; Troy et al., 2010). We adopted a 9-point scale for the assessment of self-reported efforts of cognitive reappraisal (Gruber et al., 2012). Two hypotheses related to emotion regulation across the menstrual cycle were tested: (1) highly neurotic participants reported more efforts of cognitive reappraisal in the menstrual and mid-late luteal phases than in the late follicular phase, while the self-reported efforts of participants low in neuroticism didn't differ across the menstrual cycle; (2) highly neurotic participants' emotion regulation success was smaller in the menstrual and mid-late luteal phases than in the late follicular phase, while success of participants low in neuroticism didn't differ across the menstrual cycle. 2. Method 2.1. Participants Ninety-six female graduate students completed the Revised Eysenck Personality Questionnaire Short Scale for Chinese (EPQ-RSC; Qian et al., 2000). Ultimately, 36 participants were obtained, based on their responses on the EPQ-RSC. They were divided into two groups based on their neuroticism (N) subscale scores on the EPQ-RSC, and the two groups were matched on their scores for extraversion/introversion (E), psychoticism/socialization (P), and lying (L). The highneuroticism group (HN group) contained 15 participants whose N scores were higher than the norm, and the low-neuroticism group (LN group) consisted of 21 participants whose N scores were lower than the norm. All of the participants were healthy, right-handed Chinese women with regular menstrual cycles and no diagnosis of PMS, which was screened by use of the Premenstrual Syndrome Questionnaire (PMS, Bancroft, 1993). Exclusion criteria included pregnancy, breastfeeding, use of hormonal contraception, history of substance abuse, treatment of psychotropic drugs, or presence of any ongoing psychiatric disorder. Absence of depression and anxiety symptoms was confirmed by using the Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI) for Chinese people (Wang et al., 1999).

Table 1 Demographic data and scale scores of HN group and LN group (M ± SD). LN group

Age, years Menarche age, years Menstrual phase, days Menstrual cycle, days BDI BAI EPQ-RSC

N P E L

HN group

(n = 21)

(n = 15)

t

25.10 13.33 5.19 28.71 1.48 22.67 37.25 46.79 56.62 52.34

25.27 13.20 5.87 29.93 2.80 24.87 54.71 47.00 51.29 47.83

0.53 0.32 −1.70 −1.73 −2.07⁎ −2.81⁎⁎ −18.39⁎⁎⁎ −0.80 1.50 1.53

± ± ± ± ± ± ± ± ± ±

0.89 1.24 1.29 1.49 1.33 1.62 2.93 6.93 9.89 8.88

± ± ± ± ± ± ± ± ± ±

1.03 1.21 0.99 2.71 2.48 3.04 2.63 8.78 11.27 8.57

Note: Menarche age refers to the age when menstruation first occurs in a woman's life. Menstrual phase here refers to the duration of the menstrual phase in a single menstrual cycle. Menstrual cycle here refers to the interval between two consecutive menstrual cycles. ⁎ p b 0.05. ⁎⁎ p b 0.01. ⁎⁎⁎ p b 0.001.

M. Wu et al. / International Journal of Psychophysiology 94 (2014) 351–357

Demographic characteristics and the mean scores of the scales that were mentioned above are presented in Table 1. There was a significant difference between the HN group and LN group with respect to neuroticism scores (N; t(34) = −18.39, p b 0.001), but no significant differences were observed with respect to the psychoticism (P; p = 0.937), extraversion (E; p = 0.142), and lying (L; p = 0.136) scores. The experiment was approved by the Local Ethics Committee, and informed consent was obtained from all of the participants before the experiment. The participants were paid after the experiment. 2.2. Date of experiment Each female participated in our experiment three times throughout her menstrual cycle: during the menstrual (days 1–4), late follicular (days 11–13), and mid-late luteal (days 21–23) phases. The experimental sessions extended across one or two consecutive menstrual cycles. We randomly assigned the phase during which the participants first came to our laboratory. The phase of each participant was calculated in regard to the self-reported date of her last menstrual cycle and the average length of a single menstrual cycle, which could be found in the demographic data that was collected before the experiment and was further confirmed by the estrogen and progesterone levels in her blood sample that was taken on the day of the experiment. 2.3. Hormonal assays Five milliliters of the venous blood that was collected by using a BD vacuum blood collection tube from participants who were on an empty stomach was used to measure estrogen and progesterone levels on the day of the experiment. The blood samples were stored at 4 °C for 30 min to full solidification. Then, a horizontal centrifuge with a centrifugal radius of 8 cm and a centrifugal speed of 3500 r/min was applied for 10 min to separate the serum. The serum was stored in three 1.5-ml centrifuge tubes and kept frozen at − 20 °C until the assay. Samples were determined through electrochemiluminescence by using commercial kits from Beijing Protein Innovation (Beijing, China). 2.4. Materials 2.4.1. Self-reported emotion inventory Participants' subjective emotion experience was evaluated by a selfreported emotion inventory that consisted of two global terms (pleasantness and arousal) and seven emotion terms (amusement, anger, fear, disgust, sadness, surprise, and peacefulness). Participants rated their feelings on 9-point Likert scales (1–9) for all of the terms. Specifically, for the global terms, 1 represents extremely mild or unpleasant, whereas 9 represents extremely intense/pleasant; for the emotion terms, 1 represents none and 9 represents most in my life (adapted from Gross and Levenson, 1997). This inventory was also used for appropriate film stimuli selection before the experiment. 2.4.2. Film stimuli Six high-definition film clips, each with a length of approximately 3 min, were used to elicit sadness during the current study. All of the clips were from movie and TV dramas in which all of the characters were Asian. Before the experiment, 45 female graduate and undergraduate students (mean age = 21.9, SD = 1.94) were recruited to pretest the stimuli by rating their feelings on the self-reported emotion inventory after watching the film clips. Table 2 shows the scores for the global terms and for sadness regarding the six film clips. For the six clips, sadness scored the highest of all of the emotion terms, ps b 0.05. The clips were divided into three groups for the three experimental sessions, and each group contained two sad film clips. In each group of film clips, we randomly chose one sad film clip to be reappraised, and the other one clip was to be freely watched.

353

Table 2 The scores of sadness and global terms of the six film clips used in the current study (M ± SD). Film clip

Pleasantness

Arousal

A1 A2 B1 B2 C1 C2

2.50 2.58 2.29 1.81 1.81 2.10

6.58 5.88 5.75 5.86 5.67 6.38

± ± ± ± ± ±

1.87 1.67 1.52 1.33 0.93 1.58

± ± ± ± ± ±

1.28 2.17 2.11 1.90 1.88 1.94

Sadness

n

6.58 6.38 6.63 6.76 6.19 7.14

24 24 24 21 21 21

± ± ± ± ± ±

2.55 2.18 2.43 1.92 2.09 1.59

Note: Film clip A1 and A2, B1 and B2, C1 and C2 were used in the same session.

2.5. Procedure The current study adopted a 3 (phase: menstrual, late follicular, midlate luteal) × 2 (condition: reappraisal, no reappraisal) × 2 (group: high neuroticism, low neuroticism) three-factor mixed experimental design. In regard to the three factors, phase and condition were within-subject factors, whereas the group was a between-subjects factor. Two different sets of instructions were developed for the reappraisal condition and the no reappraisal condition. In the reappraisal condition, participants received the following instructions: We will now be showing you a short film clip. It is important to us that you watch the film clip carefully until the end. This time, please try not to feel any emotion, and watch the film in terms of the technical aspects of the film. In the no reappraisal condition, participants received the following instructions: We will now be showing you a short film clip. It is important to us that you watch the film clip carefully until the end (adapted from Gross, 1998). In regard to assessment of emotion regulation efforts, after watching each film, participants rated a statement by using a 9-point Likert-type scale, ranging from 1 (strongly disagree) to 9 (strongly agree): During the film, I tried not to feel anything and concentrated on the technical aspects of the film (adapted from Gross, 1998). Each time that the participants came to the laboratory, they were asked to relax with their eyes closed for 3 min. Then, they were given the first set of instructions to either reappraise the following film or watch the film freely. The first sad film clip began after the instructions were provided, and participants were asked to complete the selfreported emotion inventory to rate their feelings after watching it and to rate their level of reappraisal effort. This was followed by a 3-min rest period to bring the participants' mood back to the baseline. Then, each participant was presented with the second set of instructions, which was different than the first one, and was allowed to watch the second sad film clip. After watching the clip, each participant was also asked to rate her feelings on the inventory and to rate her level of reappraisal effort. Each time, participants watched different films, and the order of the two conditions was balanced among participants.

2.6. Data recording Continuous physiological recordings were made by using a multichannel physical signal recording machine, namely, a BIOPAC System MP150 system. Two measures that were particularly important to emotional responding were obtained: galvanic skin response (GSR), and heart rate (HR). A GSR100C module (BIOPAC MP150) was used to measure GSR. This module measures the electrical conductance of the skin, or sweat gland activity, which are thought to be regulated by the sympathetic branch of the autonomic nervous system. The GSR level and variability of the signal increase with sympathetic arousal. This can be caused by stress, but also by emotion in general (Michael et al., 2007; Oliveira-Silva and Gonçalves, 2011). The unit of GSR is micro-siemens or micro-mho. The GSR data were collected via bipolar electrodes that were attached to the index and middle fingers of participants' left hands. The amplifier gain was 5 μmho/V, the high-pass filter was DC,

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and the low-pass filter was 10 Hz. The sample rate was 1000 Hz, and the units were μmho. The HR data were calculated through electrocardiogram (ECG) signals. ECG electrodes were attached to the participants' right ankle (GND), left ankle (VIN+) and left wrist (VIN−). The gain was set to 2000, the high-pass filter was 0.5 Hz, the low-pass filter was 35 Hz, and the sample rate was 1000 Hz. 2.7. Data analysis We extracted the GSR and HR data during the film-watching stage, both in the reappraisal condition and in the no reappraisal condition, and calculated the mean amplitude of GSR and mean HR by using Acknowledge 4.2 software. The film-watching stage began with the onset of the film clip and ended when the clip finished playing, and the length of this stage was equal to the length of the film clip, which was approximately 3 min. All of the physiological data and subjective ratings were analyzed by using SPSS 18.0 software. Three blood samples were obtained from 22 participants (8 in HN group, 14 in LN group) on the day of the experiment, and the participants' estrogen and progesterone levels were well extracted and analyzed. Three participants' physiological data were not well collected in one or more sessions; therefore, their GSR and HR data were excluded. Overall, we analyzed 33 participants' (13 in HN group, 20 in LN group) physiological data. Other data were analyzed for a sample of 36 participants (15 in HN group, 21 in LN group). 3. Results 3.1. Estrogen and progesterone levels during different phases of the menstrual cycle Twenty-two participants' estrogen and progesterone levels during different phases of the menstrual cycle are shown in Table 3. A 3 (phase: menstrual, late follicular, mid-late luteal) × 2 (group: high neuroticism, low neuroticism) mixed model analysis of variance (ANOVA) was conducted to investigate participants' hormonal fluctuations during the menstrual cycle. The results showed that the main effects of phase on estrogen (F(2,42) = 17.109, p b 0.001, ηp2 = 0.449) and progesterone levels (F(2,42) = 16.881, p b 0.001, ηp2 = 0.446) were significant, and the main effects of the group and the interactions between the group and phase were not significant. More specifically, estrogen levels during the menstrual phase were significantly lower than those during the late follicular (p = 0.001) and mid-late luteal (p b 0.001) phases, and estrogen levels during the late follicular and mid-late luteal phases did not differ significantly from each other, p = 0.218. Progesterone levels during the mid-late luteal phase were significantly higher than those during the menstrual (p b 0.001) and late follicular phases (p b 0.001), and progesterone levels during the menstrual and late follicular phases did not differ significantly from each other, p = 0.402. These results are consistent with those of previous studies of hormonal fluctuations during the menstrual cycle (for a review, see Farage et al., 2008), which confirms that the menstrual phase of the participants on the day of the experiment was correctly identified.

Table 3 Participants' estrogen and progesterone levels during the menstrual cycle (n = 22).

Estrogen Progesterone

Menstrual phase

Late follicular phase

Mid-late luteal phase

M

SE

M

SE

M

SE

187.73 5.82

22.27 2.11

526.70 9.83

77.19 3.83

647.94 33.14

52.50 5.08

F

ηp2

17.109⁎ 16.881⁎

0.449 0.446

Note: The units of estrogen levels are pmol/L and the units of progesterone levels are nmol/L. ⁎ p b 0.001.

3.2. Self-reported reappraisal levels of HN group and LN group during different phases of the menstrual cycle Reappraisal effort was indicated by participants' self-ratings (Table 4). A 3 (phase: menstrual, late follicular, mid-late luteal) × 2 (condition: reappraisal, no reappraisal) × 2 (group: high neuroticism, low neuroticism) mixed model analysis of variance (ANOVA) was conducted for the selfreported reappraisal levels. This analysis revealed a significant main effect of condition (F(1,34) = 42.155, p b 0.001, ηp2 = 0.554). Reappraisal levels were higher in the reappraisal condition than those in the no reappraisal condition, which indicated participants' compliance with the instructions. The results also showed a significant main effect due to phase (F(2,68) = 8.071, p = 0.001, ηp2 = 0.192); specifically, participants reported higher reappraisal levels during the menstrual phase than during the late follicular (p = 0.001) and mid-late luteal phases (p = 0.004). The main effect of the group and all the interactions were not significant, ps N 0.05. 3.3. Self-reported sadness of HN group and LN group under different conditions during the menstrual cycle Thirty-six participants' self-reported sadness when watching sad film clips under different conditions during the menstrual cycle are shown in Table 5. A 3 (phase: menstrual, late follicular, mid-late luteal) × 2 (condition: reappraisal, no reappraisal) × 2 (group: high neuroticism, low neuroticism) mixed model analysis of variance (ANOVA) was conducted for the data. The results showed that participants reported significantly less sadness in the reappraisal condition than in the no reappraisal condition, F(1,34) = 7.451, p = 0.010, ηp2 = 0.180. No significant main effects due to the phase or group and no significant interactions were observed, ps N 0.05. To further clarify the reappraisal success at regulating self-reported sadness, we calculated the change scores by subtracting sadness ratings that were given after the reappraisal condition from sadness ratings that were given after the no reappraisal condition. Such change scores have been widely used to index cognitive reappraisal success (McRae et al., 2012; Troy et al., 2010). A 3 (phase: menstrual, late follicular, mid-late luteal) × 2 (group: high neuroticism, low neuroticism) mixed model analysis of variance (ANOVA) was conducted in regard to the change scores, and no significant main effects of phase (F(2,68) = 0.202, p = 0.818, ηp2 = 0.006) or group (F(1, 34) = 0.013, p = 0.908, ηp2 b 0.001) and no significant interactions (F(2, 68) = 1.036, p = 0.360, ηp2 = 0.030) were found. 3.4. The regulation effects on physiological responses of HN group and LN group during the menstrual cycle Previous studies have suggested that autonomic nervous activity of healthy young women fluctuated during the menstrual cycle, both in their resting state (Usha Rani et al., 2013) and in their sad film clip watching state (Wu et al., 2014), which means that change scores that reflect the regulation effects on self-reported sadness may not be able to eliminate the baseline (no reappraisal condition) differences between the different phases of the menstrual cycle. In this regard, we used a ratio that took into account the no reappraisal condition of responding to index the reappraisal success at decreasing physiological arousal. The ratio for GSR was calculated via the following equation: (GSR in no reappraisal condition–GSR in reappraisal condition) / (GSR in no reappraisal condition + GSR in reappraisal condition) × 100%. Previous studies have found that GSR decreased after reappraisal (Yuan et al., 2011). Therefore, larger GSR change ratio was indicative of greater reappraisal success. We conducted a 3 (phase: menstrual, late follicular, mid-late luteal) × 2 (group: high neuroticism, low neuroticism) mixed model analysis of variance (ANOVA) with the ratio being the dependent variable, and the results revealed a marginally significant main effect of

M. Wu et al. / International Journal of Psychophysiology 94 (2014) 351–357

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Table 4 Self-reported reappraisal levels of HN group and LN group under different conditions during the menstrual cycle (M ± SD). Menstrual phase

Late follicular phase

Mid-late luteal phase

Condition

LN group (n = 21)

HN group (n = 15)

LN group (n = 21)

HN group (n = 15)

LN group (n = 21)

HN group (n = 15)

No reappraisal Reappraisal

4.57 ± 2.580 6.62 ± 1.658

4.47 ± 2.696 5.87 ± 2.416

3.33 ± 2.517 5.67 ± 1.880

3.00 ± 1.648 4.67 ± 2.410

3.19 ± 1.778 5.81 ± 2.136

2.73 ± 2.052 5.73 ± 1.870

Note: The main effect of condition was significant, no reappraisal b reappraisal (p b 0.001); the main effect of phase was significant, menstrual phase N late follicular phase (p = 0.001) & mid-late luteal phase (p = 0.004); the main effect of neuroticism group and the interactions were not significant (ps N 0.05).

phase, F(2,62) = 2.907, p = 0.062, ηp2 = 0.086. Specifically, the change ratio of GSR during the menstrual phase was significantly smaller than that during the mid-late luteal phase, p = 0.048, and it was slightly smaller than that during the late follicular phase, p = 0.082. There was no significant difference between the change ratio during the late follicular phase and during the mid-late luteal phase, p = 0.656 (see Fig. 1). The main effect of the group and the interaction between the group and phase were not significant, ps N 0.05. These results suggested that participants' emotion regulation success during the menstrual phase were the least throughout the menstrual cycle, regardless of the participants' neuroticism levels. In regard to HR, we calculated the change ratio via the following equation: (HR in no reappraisal condition–HR in reappraisal condition) / (HR in no reappraisal condition + HR in reappraisal condition) × 100%. However, we found no significant main effects of the phase (F(2, 62) = 0.828, p = 0.442, ηp2 = 0.026) or group (F(1, 31) =0.829, p = 0.369, ηp2 = 0.026), and the interaction was also not significant (F(2, 62) = 0.361, p = 0.698, ηp2 = 0.012). 4. Discussion The purpose of this study was to investigate whether women's efforts and success at using cognitive reappraisal to regulate their emotions would be affected by the menstrual cycle and neuroticism levels. Our findings suggested that the menstrual cycle did have an effect on women's emotion regulation. Women in the menstrual phase made more efforts to regulate their emotions by using reappraisal, which was indicated by higher self-reported reappraisal levels, but the regulation success was not larger than those during the other two phases, which was indicated by GSR and self-reported sadness. Self-reported sadness did not differ between the three phases, and the regulation effect on GSR during the menstrual phase was even smaller than that of the mid-late luteal phase. This may help to explain why women exhibit intense emotional responses despite their strong intent to engage in emotion regulation during the menstrual phase. In the current work, we found that women expended more efforts to regulate their emotions in the menstrual phase than they did in the other two phases. Previous studies have also implied that the menstrual cycle may influence emotion regulation efforts. Hwang et al. (2009) found that left frontal activity was higher during the menstrual phase than in the late follicular phase when participants were presented with fearful faces, and Protopopescu et al. (2005) found that orbitofrontal cortex (OFC) activity for negative vs. neutral linguistic

stimuli increased in the luteal phase and decreased in the follicular phase. As we mentioned before, the left frontal cortex and OFC have been implicated in emotion regulation (for a review, see Phillips et al., 2008). These findings thus indicated that women called more cognitive neural resources to suppress negative emotion in the menstrual or luteal phase, which further implied that women made more efforts to regulate emotions in these two phases. However, Hwang et al. (2009) and Protopopescu et al. (2005) didn't compare participants' performances during the menstrual phase with those during the luteal phase, so they failed to clarify the influence of the menstrual cycle on emotion regulation efforts in a comprehensive view. According to the results of participants' subjective experience and physiological responses, although they reported higher levels of reappraisal during the menstrual phase, the emotion regulation success did not appear to be larger during this phase. Firstly, the change scores of self-reported sadness did not differ significantly during the three different phases, which meant that more emotion regulation efforts did not cause a greater decrease in self-report sadness. Secondly, the change ratio of GSR was smallest during the menstrual phase. Previous researchers have suggested that reappraisal would certainly cause a decrease in GSR when evoked by emotional stimuli (Yuan et al., 2011), which meant that higher change ratios were associated with better participant performance in emotion regulation. Therefore, reappraisal success seemed less in the menstrual phase as compared to the other two phases. Thirdly, the change ratio of HR did not differ between the three different phases. Researchers have indicated that the regulation effect of reappraisal on HR can only be observed when participants are asked to up-regulate their emotions (Giuliani et al., 2008), and when they are asked to downregulate negative emotions, the regulation effect may not be observed (Yuan et al., 2011). The current study investigated the down-regulation of sadness; therefore, GSR was selected to reflect the effect of emotion regulation. Additionally, consistent with Wu et al. (2014), the results of self-reported sadness showed that the menstrual cycle did not affect subjective experiences of sadness. Ossewaarde et al. (2010) used both physiological measures and self-reports to index participants' emotional responses across the menstrual cycle, and the results showed that the influence of the menstrual cycle on emotional response could only be found on physiological measures rather than self-reports. Some studies in regard to women's emotional responses across the menstrual cycle used brain imaging techniques, and didn't collect self-reported data (Andreano and Cahill, 2010; Gingnell, et al., 2012). Thus, the influence of the menstrual cycle on subjective experience remains unclear and requires future studies to investigate.

Table 5 Self-reported sadness of HN group and LN group when watching sad film clips under different conditions during the menstrual cycle (M ± SD). Menstrual phase

Late follicular phase

Mid-late luteal phase

Condition

LN group (n = 21)

HN group (n = 15)

LN group (n = 21)

HN group (n = 15)

LN group (n = 21)

HN group (n = 15)

No reappraisal Reappraisal

5.90 ± 2.19 5.57 ± 2.27

5.53 ± 1.81 5.00 ± 2.04

5.76 ± 2.36 4.76 ± 2.28

5.20 ± 2.46 5.13 ± 2.33

5.95 ± 2.20 5.57 ± 1.91

6.73 ± 2.19 5.47 ± 1.60

Note: The main effect of condition was significant, no reappraisal N reappraisal (p = 0.010); no significant main effects due to phase or group and no significant interactions were observed, ps N 0.05.

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be the reason why the change scores of sadness and the change ratio of GSR were so small in our study (see Table 5 and Fig. 1). It will, thus, be important for future work to resolve this issue by using a well-designed paradigm and a larger sample. Third, the assessment of emotion regulation efforts was based on self-report. As such, the accuracy of these estimates could be susceptible to potential demand characteristics. Fourth, although we did not tell participants the purpose and hypotheses of our study, all of the participants were asked about the basic information of their menstrual cycle before the experiment, and they came to our lab during specific phases of their menstrual cycle, so they may have known that the menstrual cycle would be one of our concerns. The open-label experimental design does not allow us to thoroughly exclude participants' expectations about the link between emotions and the menstrual cycle. 5. Conclusions Fig. 1. Change ratio for GSR during the reappraisal condition as compared to the no reappraisal condition across the menstrual cycle for HN group and LN group. Note: The ratio for GSR was calculated via the equation (GSR in no reappraisal condition–GSR in reappraisal condition) / (GSR in no reappraisal condition + GSR in reappraisal condition) × 100%. The main effect of phase was marginally significant, menstrual phase b mid-late luteal phase (p = 0.048) & late follicular phase (p = 0.082). The main effect of the group and the interaction between the group and phase were not significant, ps N 0.05.

Women's emotion regulation can be affected by the menstrual cycle. Women expend more efforts but gain less success at emotion regulation during the menstrual phase than during the premenstrual or postmenstrual phase. Neuroticism levels have no impact on women's emotion regulation. Declaration of interest

Emotion dysregulation has long been thought to be a vulnerability factor for mood disorders (Ehring et al., 2010). Researchers found that recovered-depressed participants reported to have spontaneously used suppression during a sadness-inducing film more often than never-depressed controls (Ehring et al., 2010); comparing with healthy controls, participants with bipolar disorder reported greater effort, but less success, when spontaneously regulating emotions induced by emotion film clips (Gruber et al., 2012); participants with generalized anxiety disorder (GAD) demonstrated lower cardiac flexibility when implementing adaptive regulation strategies than when not given specific instructions on how to regulate, whereas healthy controls showed the opposite pattern, suggesting that participants with GAD didn't benefit from the use of adaptive regulation strategies (Aldao and Mennin, 2012). The findings of the current study indicated that women may have emotion dysregulation during their menstrual phase. As such, women may need more help to prevent themselves from mood disorders during the menstrual phase. We did not find any impact of neuroticism on women's emotion regulation. However, a previous study found that highly neurotic women were more vulnerable during their menstrual cycle and that their emotional responding was more intense during the menstrual phase (Wu et al., 2014), which may suggest that the effect of neuroticism levels on women's emotional responding is mainly in regard to emotional reactivity rather than emotion regulation. This hypothesis requires further investigation. Our current work had several limitations. First, cell sizes of our study were small, especially for physiological and hormonal measures that had missing values, which may distract us from pursuing the discoveries of the effects of neuroticism levels on emotion regulation. Although we tested women's hormonal levels during the menstrual cycle, which would be a chance to reveal the neuroendocrine mechanism that underlies women's emotion regulation, only having the hormone results of 22 participants did not allow us to accomplish this goal. Second, we balanced the order of the reappraisal condition and the no reappraisal condition, which meant that for half of the trials, the “no reappraisal” instructions followed the “reappraisal” instructions. Given that participants may just have reappraised during the first film clip, they may continue to reappraise the sad film clip in the no reappraisal condition. Although self-reported reappraisal levels and sadness were lower in the reappraisal condition than the no reappraisal condition, the no reappraisal trials might also contain some amount of reappraisal, which may

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