Abstract
Objective
An emerging literature provides evidence for the association between romantic relationship quality and sleep, an important factor in health and well-being. However, we still know very little about the specific relationship processes that affect sleep behavior. Therefore, the goal of this study was to examine how self-disclosure, an important relational process linked to intimacy, relationship satisfaction and health, is associated with sleep behavior.
Method
As part of a larger study of family processes, wives (n=46) and husbands (n=38) from 46 cohabiting families completed 56 days of daily diaries. Spouses completed evening diaries assessing daily self-disclosure, relationship satisfaction, and mood and morning diaries assessing the prior night's sleep. Multilevel modeling was used to explore the effects of both daily variation in and average levels across the 56 days of self-disclosure on sleep.
Results
Daily variation in self-disclosure predicted sleep outcomes for wives, but not for husbands. On days when wives self-disclosed more to their spouses than their average level, their subjective sleep quality and sleep efficiency that night improved. Furthermore, daily self-disclosure buffered the negative effect of daily negative mood on sleep latency for wives, but not husbands. In contrast, higher average levels of self-disclosure predicted less waking during the night for husbands, but not for wives.
Conclusion
The association between self-disclosure and sleep is one mechanism by which daily relationship functioning may influence health and well-being. Gender may play a role in how self-disclosure is associated with sleep.
Keywords: Self-disclosure, Sleep Quality, Sleep Efficiency, Couples, Daily Diary
Happy and satisfying marriages are associated with health benefits, whereas unhappy or ambivalent marriages are associated with health detriments (Kiecolt-Glaser & Newton, 2001; Robles, Slatcher, Trombello & McGinn, in press). Sleep may partially explain the association between marriage and health (Troxel, 2010). Despite the fact that approximately 70% of adults sleep in the same bed with a significant other (National Sleep Foundation, 2011) and relationship difficulties often co-occur with sleep disturbance, only recently have investigators approached the study of sleep as a dyadic process embedded in the marital context (Troxel, Robles, Hall, & Buysse, 2007; Troxel, 2010).
Little is known about the specific daily relationship processes that may influence sleep. Only a few studies have examined daily assessments of couples' interactions and sleep (Hasler & Troxel, 2010; Hicks & Diamond, 2011). Self-disclosure, the act of revealing personal thoughts and feelings, is an important interpersonal process that may influence sleep. An optimal sleep environment requires the down regulation vigilance and arousal and the up regulation of safety and security (Dahl, 1996). Self-disclosure to spouses may be associated with sleep by facilitating an optimal sleep environment. To our knowledge, the association between self-disclosure and sleep has never been explored.
Self-disclosure of thoughts and feelings about stressful experiences is associated with health improvements over time including sleep. However, almost all of this prior work has examined written self-disclosures (Pennebaker & Chung, 2011). For example, in a small university sample of individuals meeting criteria for sleep disturbance on the Pittsburgh Sleep Quality Index, writing thoughts and feelings about traumatic experiences predicted diary-reported shorter time to fall asleep (Harvey & Farrell, 2003), although this effect was not replicated in a small sample of insomnia patients (Mooney, Espie, & Broomfield, 2009). Additionally, in an experimental study, healthy sleepers randomly assigned to write thoughts and feelings about an induced failure experience showed greater sleep efficiency and less time awake after falling asleep (assessed via polysomnography) compared to participants assigned to write in a more analytical manner (Vandekerckhove et al., 2012). In everyday life, self-disclosure between spouses is much more likely to occur than written self-disclosures. Yet surprisingly, very few studies have examined the effects of self-disclosure in interpersonal contexts on health-related outcomes.
Self-disclosure to spouses may enhance feelings of safety and security in the relationship and in turn, the sleep environment. Safety and felt security are derived in part from marriages in which partners are close, responsive to each other's needs, and value, accept, trust and understand each other (Collins & Feeney, 2004). The presence of close, responsive partners reduces psychological, neural, and physiological responses to threat (e.g., Coan, Schaefer, & Davidson, 2006; Diamond & Hicks, 2004; Kane, McCall, Collins & Blascovich, 2012) that can interfere with sleep. Furthermore, close relationships can protect against perceived loneliness and isolation which are also associated with poor sleep (Hawkley & Cacioppo, 2010). Thus, self-disclosure may be associated with sleep because it promotes intimacy and closeness in relationships (Reis & Shaver, 1988), which can further promote felt security. Emotional self-disclosures that are particularly relevant to the self, compared to merely sharing facts, are particularly beneficial to relationships (Reis & Shaver, 1988; Laurenceau, Barrett & Pietromonaco, 1998), and should also be particularly beneficial to sleep.
Sleep occurs within the overall context of daily experiences, and negative appraisals and emotional responses to daily events are associated with sleep disturbance. In healthy adults (Akerstedt et al., 2012; Brissette & Cohen, 2002; Morin, Rodrigue & Ivers, 2003), greater self-reported negative affect and stress ratings during the day predicted poorer subjective sleep quality that night in daily diary studies ranging from 7 days to 6 weeks. In addition, higher self-reported stress and worry at bedtime was related to lower sleep efficiency and more minutes awake after falling asleep assessed by at-home polysomnography (Akerstedt, Kecklund, & Axelsson, 2007).
Self-disclosure may improve coping and reduce negative mood that can impair sleep. Self-disclosure, in particular emotional disclosure, may aid in coping by decreasing worry, ruminative thought patterns and arousal (for reviews see Greene, Derlega & Mathews, 2006; Pennebaker & Chung, 2011). Emotional self-disclosure may also elicit greater support provision from spouses. Indeed, self-disclosure to a spouse buffers individuals from the negative effects of work worries on physiological stress responses (Slatcher, Robles, Repetti & Fellows, 2010). Thus, self-disclosure may mitigate the association between negative mood and sleep disturbance.
Conversely, in the context of positive mood, daily self-disclosure may promote relationship satisfaction and individual well-being through sharing positive experiences. The social sharing of positive events confers added benefit to self-esteem and relationship satisfaction over and above the effect of the event itself, allowing individuals to relive positive experiences, make them more salient in their memories, and foster positive social interactions (Gable, Reis, Impett & Asher, 2004). Thus, self-disclosure in the context of positive mood may provide an added benefit over and above merely self-disclosing.
The present study measured daily spousal self-disclosure, daily positive and negative mood, and sleep outcomes in 46 couples over 56 days. Most of the research on sleep disturbances is guided by insomnia research and recommendations and reporting standards have been developed for research assessments (Buysse, Ancoli-Israel, Edinger, Lichstein, & Morin, 2006). The sleep outcomes assessed in this study represent the most common sleep disturbances (insomnia symptoms) affecting 30-48% of the population (Ohayon, 2002). They include both difficulty falling sleep (long sleep onset latency, SOL) and difficulty staying asleep (greater waking after sleep onset, WASO). Furthermore, sleep efficiency, time in bed asleep relative to total time in bed, is a key construct in sleep research. It is calculated by subtracting WASO and SOL from the total time in bed to produce sleep duration and then dividing by the total time in bed. So, although sleep efficiency, WASO, SOL and sleep duration are interrelated they are frequently analyzed separately in the literature because they assess different sleep problems (Buysse et al, 2006). For example, SOL and WASO provide insight into the particular part of sleep that may be disrupted (the beginning of the night trying to fall asleep or later in the night trying to stay asleep) and may have differential health effects (Dew et al., 2003). Therefore, in accord with reporting standards, the sleep outcomes measured in this study included subjective sleep quality, sleep efficiency, SOL, WASO and sleep duration (Buysse et al, 2006; Morin, 2003).
The primary hypothesis that greater daily self-disclosure to spouses would be associated with better sleep, even after accounting for daily positive and negative mood and relationship satisfaction was tested first. Next the hypothesis that daily self-disclosure would buffer the effect of daily negative mood on sleep, and enhance the effects of daily positive mood on sleep was tested. Then analyses to test the degree to which one's partner's report of his/her own daily self-disclosure predicted the other partner's sleep were conducted. Given prior research showing that partner self-disclosure is also beneficial for relationships (e.g., Laurenceau et al., 1998; Laurenceau et al., 2005), it was hypothesized that greater daily partner self-disclosure would also be associated with better sleep. Finally, because the associations between sleep and relationship experiences can be bidirectional (Hasler & Troxel, 2010) and sleep deprivation is associated with decreased observed emotional expressiveness (Minkel, Htaik, Banks & Dinges, 2011), the extent to which the prior night's sleep quality and efficiency influenced self-disclosure the following day was also tested.
Method
Participants
Families (N = 47) were recruited from the greater Los Angeles area as part of a study examining family dynamics and upper respiratory infections in children ages 8-13 (Robles, Reynolds, Repetti & Chung, 2013). To minimize study burden on participating families, only one parent was required to participate although both parents were encouraged. The present analyses included two-parent, cohabiting families, resulting in a sample of 46 wives (M age = 43.2 years, SD = 6.33, range 28.5 – 54.1) and 38 husbands (M age = 43.7, SD = 8.26, range = 27.7 – 62.0), in a married or marriage-like relationship for an average of 16.33 years (SD = 6.62, range = 1.3 – 27.6). Median personal income was within the $31,851-$64,250 tax bracket for the first two cohorts and $34,001- $82,400 for the third cohort. Couple members were 46% non-Hispanic white, 19% Latino/Hispanic, 18% African-American, 13% Asian, 1% Native American and 2% “Other”. The average couple reported high relationship satisfaction (wives M = 116.2, SD = 28.07, range = 44-154; 23.9% distressed; husbands M = 124.4, SD = 22.1, range = 57-159; 18.4% distressed) (Funk & Rogge, 2007). Participants were screened for medications and medical conditions that might affect biological measures collected in the study1.
Procedure
Spouses completed an 8-week (56 day) daily diary and sleep diary beginning on a Saturday using online or paper diaries. Daily dairies were completed before bedtime and sleep diaries were completed in the morning after waking. Online diaries were automatically date/time stamped and paper diaries were electronically date/time stamped (Dymo #47002) and mailed to the laboratory the day after completion. Several measures were taken to encourage compliance, and participants were highly compliant in their completion (for a detailed description see Robles et al., 2013).
Daily relationship measures
To measure self-disclosure, participants completed a 2-item measure (Laurenceau et al., 1998) that assessed the degree to which they disclosed their thoughts and feelings to their spouses (Rc, wives = .90, Rc, husbands = .91) on a scale from 1 “not at all” to 5 “extremely”2, 3. This measure of self-disclosure is based on the interpersonal process model of intimacy (Reis & Shaver,1988) and has been widely used in daily diary research (Laurenceau et al., 1998; Laurenceau, et al., 2005). Participants also completed a single item assessing daily relationship satisfaction (Gable, Reis, & Downey, 2003) on a scale from 1 “Terrible” to 7 “Terrific”. Relationship satisfaction person means (averaged over 56 days) were highly correlated with the CSI (Couples Satisfaction Inventory: Funk & Rogge, 2007), a well-validated self-report measure of relationship satisfaction (rwives = .58, p<.001, rhusbands = .65, p <.001).
Daily positive and negative mood measures
Participants rated how accurately each of a series of adjectives described how they felt over the past 24 hours on a scale from 1 “not at all accurate” to 4 “extremely accurate” (Cohen et. al., 2006). The adjectives for positive mood (Rc,wives = .81, Rc,husbands = .79) were at ease, calm, full of energy, lively, happy and cheerful. The adjectives for negative mood (Rc,wives = .80, Rc,husbands = .82) were on edge, tense, sad, unhappy, hostile and angry. The average daily correlations between positive and negative mood were rwives=-.37 (SD = .12) and rhusbands=-.20 (SD = .12). Person mean (averaged over 56 days) correlations between positive and negative mood were rwives = -.32, p = .03 and rhusbands = -.05, p = .75.
Sleep outcomes
Participants completed a modified version of the Pittsburgh Sleep Diary (Monk et al., 1994). To measure subjective sleep quality participants rated the quality of their sleep on a single item ranging from 1 “Terrible” to 8 “Great.” Sleep efficiency is the number of minutes participants reported being asleep from sleep initiation to final awakening divided by the number of minutes they reported being in bed, expressed as a percentage (with 7 hours asleep and 8 hours in bed, sleep efficiency = 87.5%). Sleep efficiency is derived from both SOL and WASO. For SOL participants reported how many minutes it took them to fall asleep, and for WASO participants reported the total time in minutes of awakenings experienced after falling asleep. Sleep duration was calculated in hours by measuring a participants total time in bed (time went to bed – time out of bed) and then subtracting WASO and SOL. Subjective sleep quality was modestly related to the other time-based sleep outcomes in expected directions (|r|'s from .3 - .6, with the exception of husband's subjective sleep quality and sleep duration, r = .08). On average, participants reported sleeping fairly well (SOL < 30 min, WASO < 30 min, sleep efficiency > 85%, sleep duration > 6 hours; Buysse et al., 2006), with high subjective sleep quality (Table 1).
Table 1.
Descriptive statistics for the primary variables.
Variable | Wives Mean (SD) |
Husbands Mean (SD) |
---|---|---|
Daily Diary Variables | ||
Self-disclosure | 3.05 (1.00) | 3.03 (0.92) |
Positive mood | 2.76 (0.67) | 2.82 (0.61) |
Negative mood | 1.36 (0.48) | 1.30 (0.45) |
Relationship satisfaction | 5.18 (0.99) | 5.25 (0.85) |
Sleep Diary Variables | ||
Subjective sleep quality | 6.21 (1.40) | 6.05 (1.33) |
Sleep efficiency (%) | 95.14 (7.14) | 95.54 (6.92) |
Sleep onset latency (SOL), min | 11.23 (16.31) | 10.29 (13.62) |
Waking after sleep onset (WASO), min | 11.08 (24.34) | 10.04 (27.101) |
Sleep duration (hr) | 7.37 (1.47) | 7.15 (1.43) |
Note: Descriptive statistics were calculated as averages across all participants and all 56 days. nwives= 46, nhusbands = 38.
Analytic Strategy
Multilevel modeling (MLM) is ideal for the hierarchical structure of our data (56 daily observations are nested within persons) and it accounts for between-person variation (individual deviation from the grand mean) and within-person variation (an individual's daily deviation from their own 56-day mean). Due to different sample sizes for men and women, separate models for husbands and wives were estimated first and then dyadic models were estimated with both husbands and wives simultaneously. To explicitly model between- and within-person variation, each daily predictor of interest (self-disclosure, mood and relationship satisfaction) was represented by two variables (Hoffman & Stawski, 2009). For a given participant and predictor, one variable represented between-person variation (designated by the subscript BP), defined as the participant's average across all days (person mean), and centered so that 0 was the grand mean. Thus, self-disclosureBP was equal to a participant's self-disclosure ratings averaged across all study days. For each predictor, a second variable represented within-person variation (subscript WP) defined as deviation from the person's mean on a particular day. Thus, for a participant with self-disclosureBP = 2 and self-disclosure rating on day 32 = 3, self-disclosureWP = 1 on day 32. Modeling between-person and within-person variation more accurately reflects the inherent association between daily behavior and individual differences (Hoffman & Stawski, 2009). Models were estimated using maximum likelihood estimation and an autoregressive AR(1) error structure for the repeated measures using SPSS 18 software (IBM PASW).
Sleep efficiency, SOL, and WASO were fairly skewed so we log10(x + 1) transformed these variables to correct for any potential bias. Sleep efficiency was negatively skewed, so it was reflected by subtracting each value from 101 to make it positively skewed and thus appropriate for transformation (Tabachnick & Fidell, 2007). Reflecting sleep efficiency reversed its direction (best = 1, worst = 101). Therefore, to simplify the interpretation the original direction (high values = better sleep efficiency) was restored by multiplying the parameter coefficients for analyses predicting sleep efficiency by -1 in the tables and the text.
First, using MLM, sleep was predicted as a function of daily self-disclosure. Because relationship satisfaction and mood have been associated with sleep in prior daily studies (Hasler & Troxel, 2010; Troxel, et al., 2007), sleep was then predicted as a function of self-disclosure adjusting for relationship satisfaction and positive and negative mood. Second, sleep was predicted as a function of the interaction between daily self-disclosure and daily mood . Third, using couples with complete data from both partners (Ncouples = 38), an Actor-Partner Interdependence Model (Kenny, Kashy & Cook, 2006) was estimated to simultaneously assess the effect of actor and partner self-disclosure on sleep outcomes. This model examined how wives' (actor) and husbands' (partner) self-disclosure predicted wives' sleep and vice versa. In this APIM, contrasts were conducted to statistically test for gender differences in the effects of self-disclosure on sleep (Kenny, Kashy & Cook, 2006). Finally the alternative explanation that sleep the night before may affect self-disclosure the following day was tested. Self-disclosure was predicted as a function of the prior night's sleep (subjective sleep quality and sleep efficiency in separate models) for both wives and husbands.
Results
Wives' Self-disclosure and Sleep
As shown in Table 2, wives who self-disclosed more in general (self-disclosureBP) did not have better subjective sleep quality or sleep efficiency. However, subjective sleep quality, sleep efficiency and sleep duration were higher on days when wives reported more than their average self-disclosure (self-disclosureWP) compared to days when wives reported less than their average self-disclosure. For example, given a participant who typically spends 8 hours in bed, a 1 point increase in self-disclosure ratings above one's average self-disclosure level (self-disclosureBP) would result in a 0.35 percentage point increase in sleep efficiency, which translates to an additional 1.5 minutes of sleep. The effect of self-disclosureWP on sleep efficiency was primarily due to less WASO, rather than shorter SOL (Table 2). A 1 unit increase in self-disclosure ratings above self-disclosureBP resulted in a 0.58 minute decrease in WASO. Furthermore, self-disclosureWP remained a significant predictor of sleep quality, sleep efficiency, WASO and sleep duration after adjusting for daily relationship satisfaction, positive mood and negative mood (Table 3).
Table 2. Associations between Self-disclosure and Sleep Outcomes.
Predictor | Subjective sleep quality | Sleep efficiencya,b | SOLa | WASOa | Sleep duration |
---|---|---|---|---|---|
Wives | |||||
Self-disclosureBP | 0.20 (0.19) | 0.02 (0.05) | 0.01 (0.07) | -0.02 (0.09) | 0.23 (0.18) |
Self-disclosureWP | 0.12 (0.03)** | 0.04 (0.01)*** | -0.01 (0.01) | -0.07 (0.01)*** | 0.10 (0.04)** |
Husbands | |||||
Self-disclosureBP | 0.19 (0.22) | 0.11 (0.06)† | -0.05 (0.07) | -0.25 (0.10)* | 0.10 (0.20) |
Self-disclosureWP | 0.03 (0.04) | 0.01 (0.01) | 0.00 (0.01) | -0.00 (0.02) | 0.06 (0.05) |
Note. Parameter estimates are unstandardized beta coefficients, with SE in parentheses. nwives= 46, nhusbands = 38, WP = within-person, BP = between-person,
log10(x+1) transformed variables,
coefficient multiplied by -1,
p<.001,
p<.01,
p<.05,
P<.10.
Table 3. Associations between Self-disclosure and Sleep Outcomes adjusting for Daily Mood and Relationship Satisfaction.
Predictor | Subjective sleep quality | Sleep efficiencya,b | SOLa | WASOa | Sleep duration |
---|---|---|---|---|---|
Wives | |||||
Self-disclosureBP | -0.26 (0.24) | -0.05 (0.07) | 0.12 (0.11) | -0.01 (0.13) | 0.22 (0.27) |
Self-disclosureWP | 0.09 (0.04)* | 0.03 (0.01)** | -0.01 (0.01) | -0.06 (0.02)*** | 0.11 (0.04)** |
Negative moodBP | 0.03 (0.36) | 0.30 (0.11)** | -0.36 (0.16)* | -0.33 (0.19)† | -0.25 (0.40) |
Negative moodWP | -0.04 (0.08) | 0.02 (0.02) | -0.00 (0.02) | -0.06 (0.04)† | -0.20 (0.09)* |
Positive MoodBP | 0.86 (0.22)*** | 0.24 (0.07)** | -0.13 (0.10) | -0.41 (0.12)** | 0.37 (0.25) |
Positive MoodWP | 0.23 (0.06)*** | 0.04 (0.02)* | -0.02 (0.02) | -0.07 (0.03)* | 0.19 (0.07)** |
Relationship SatisfactionBP | 0.34 (0.25) | 0.06 (0.08) | -0.16 (0.11) | 0.08 (0.13) | -0.15 (0.28) |
Relationship SatisfactionWP | 0.04 (0.04) | 0.00 (0.01) | -0.00 (0.01) | 0.01 (0.02) | -0.04 (0.04) |
Husbands | |||||
Self-disclosureBP | -0.47 (0.23)* | 0.12 (0.07) | -0.02 (0.09) | -0.35 (0.12)** | 0.21 (0.26) |
Self-disclosureWP | 0.02 (0.04) | 0.00 (0.01) | 0.01 (0.01) | -0.01 (0.02) | 0.03 (0.05) |
Negative moodBP | 1.00 (0.36)** | 0.17 (0.11) | -0.15 (0.13) | -0.16 (0.18) | 0.49 (0.41) |
Negative moodWP | -0.15 (0.09)† | -0.02 (0.02) | 0.03 (0.03) | 0.01 (0.04) | 0.05 (0.11) |
Positive MoodBP | 0.61 (0.23)* | 0.11 (0.07) | -0.07 (0.08) | -0.26 (0.12)* | -0.16 (0.26) |
Positive MoodWP | 0.07 (0.08) | 0.02 (0.02) | -0.02 (0.02) | 0.03 (0.04) | 0.13 (0.10) |
Relationship SatisfactionBP | 1.26 (0.29)*** | -0.01 (0.09) | -0.07 (0.11) | 0.19 (0.15) | -0.10 (0.33) |
Relationship SatisfactionWP | 0.02 (0.04) | 0.00 (0.01) | -0.02 (0.01) | 0.02 (0.02) | 0.06 (0.05) |
Note. Parameter estimates are unstandardized beta coefficients, with SE in parentheses. nwives= 46, nhusbands = 38, WP = within-person, BP = between-person,
log10(x+1) transformed variables,
coefficient multiplied by -1,
p<.001,
p<.01,
p< .05,
p<.10.
Self-disclosure and daily mood
As shown in Table 3, there were significant independent effects of positive moodWP and self-disclosureWP on subjective sleep quality, sleep efficiency, sleep duration, and WASO, demonstrating that on days when wives reported above average positive mood and above average self-disclosure, their sleep was better relative to only above average self-disclosure or above average positive mood. Additionally, greater positive mood averaged across the 56 days (positive moodBP) was associated with better subjective sleep quality, sleep efficiency and shorter WASO. Unexpectedly, wives reporting greater negative mood averaged across the 56 days (negative moodBP) had shorter SOL and accordingly higher sleep efficiency. However, in analyses including negative mood as the only predictor, negative moodBP was not significantly related to any sleep outcomes (p's from .09 - .51), although the marginal findings (p < .15) were such that greater negative moodBP was related to shorter SOL and higher sleep efficiency. In these analyses, days with worse negative mood relative to one's own average (negative moodWP) were characterized by poorer subjective sleep quality, b = -0.18, SE = 0.07, p = .01, and shorter sleep duration, b = -0.26, SE = 0.08, p = .001, similar to the results in Table 3.
Next the hypotheses that self-disclosure would be especially beneficial for sleep on days when wives reported greater than their average negative mood or greater than average positive mood were tested. The self-disclosureWP × negative moodWP interaction adjusting for relationship satisfaction and positive mood was significant for sleep latency, b = -0.04, SE = 0.02, p = .05. The regions of significance for this interaction (www.quantpsy.org; Preacher et al., 2006) were explored and revealed that the negative association between self-disclosureWP and SOL was significant on days when women reported negative mood at least 0.66 points (1.83 SDWP) above their average negative mood (Figure 1). Thus, greater self-disclosure relative to one's average over 56 days was related to shorter SOL, but only on days characterized by very high negative mood. The interaction between self-disclosureWP and positive moodWP adjusting for relationship satisfaction and negative mood, did not significantly predict sleep.
Figure 1. Interaction of Wives' Daily Negative Mood and Self-disclosure on Wives' Sleep Latency.
Husbands Self-disclosure and Sleep
As shown in Table 2, husbands who self-disclosed more on average (self-disclosureBP) had less WASO. For a husband with an average self-disclosure = 1, average WASO was 8.75 minutes; if average self-disclosure = 5, average WASO was less than one minute. Neither self-disclosureBP nor self-disclosureWP was significantly associated with any other sleep outcomes. After adjusting for relationship satisfaction and daily mood, self-disclosureBP remained significantly associated with WASO. Additionally, an apparent suppression effect emerged such that greater self-disclosureBP was associated with poorer sleep quality (Table 3). Both greater negative moodBP and positive moodBP significantly predicted better subjective sleep quality, and greater positive moodBP also predicted shorter WASO. Finally, the interaction effects (self-disclosureWP × negative moodWP and self-disclosureWP × positive moodWP) predicting sleep were not significant indicating that self-disclosure was not especially beneficial for sleep on days when husbands reported greater negative mood or positive mood.
Actor-Partner Effects of Self-disclosure on Sleep
Among wives, actor effects remained relatively unchanged (Table 4) except that greater self-disclosureWP now significantly predicted shorter SOL. Among husbands, several actor and partner effects emerged (Table 4). For husbands, higher average self-disclosure ratings (actor self-disclosureBP) were associated with significantly better sleep efficiency, due to shorter SOL and less WASO. For a husband with self-disclosureBP = 1, average sleep efficiency = 90.2%, SOL = 16.2 min, and WASO = 19.5 min. In contrast, for a husband with self-disclosureBP = 5, average sleep efficiency = 99.8%, SOL = 2.3 min, and WASO = 0 min. Interestingly, higher wives' average self-disclosure ratings (partner self-disclosureBP) were associated with significantly lower husbands' sleep efficiency due to significantly longer SOL. For a wife reporting self-disclosureBP = 1, her husband's average sleep efficiency = 99.4%, and SOL = 1.4 min. In contrast, for a wife reporting self-disclosureBP = 5, her husband's average sleep efficiency = 92.8%, and SOL = 21.6 min.
Table 4. Actor-Partner Effects of Self-Disclosure Predicting Sleep Outcomes.
Predictor | Subjective sleep quality | Sleep efficiencya,b | SOLa | WASOa | Sleep duration |
---|---|---|---|---|---|
Wives | |||||
Actor effects | |||||
Self-disclosureBP | 0.08 (0.28) | 0.00 (0.09) | -0.03 (0.12) | 0.02 (0.15) | -0.09 (0.29) |
Self-disclosureWP | 0.11 (0.04)** | 0.04 (0.01)*** | -0.02 (0.01)* | -0.07 (0.02)*** | 0.10* (0.04) |
Partner effects | |||||
Self-disclosureBP | 0.22 (0.27) | 0.04 (0.09) | 0.05 (0.12) | -0.12 (0.14) | 0.35 (0.28) |
Self-disclosureWP | 0.04 (0.05) | -0.00 (0.01) | -0.01 (0.01) | 0.00 (0.02) | 0.01 (0.05) |
Husbands | |||||
Actor effects | |||||
Self-disclosureBP | 0.40 (0.31) | 0.23 (0.07)** | -0.18 (0.08)* | -0.42 (0.13)** | -0.06 (0.27) |
Self-disclosureWP | 0.04 (0.04) | 0.01 (0.01) | 0.01 (0.01) | -0.01 (0.02) | 0.04 (0.05) |
Partner effects | |||||
Self-disclosureBP | -0.29 (0.32) | -0.18 (0.08)* | 0.19 (0.08)* | 0.24 (0.13) † | 0.26 (0.28) |
Self-disclosureWP | 0.00 (0.03) | 0.01 (0.01) | -0.01 (0.01) | -0.02 (0.02) | 0.06 (0.04) |
Note. Parameter estimates are unstandardized beta coefficients, with SE in parentheses. n= 38 couples, WP = within-person, BP = between-person,
log10(x+1) transformed variables,
coefficient multiplied by -1,
p<.001,
p<.01,
p≤ .05,
p<.10.
Gender differences
Gender differences in the actor and partner effects of self-disclosure were explored by testing contrasts between husbands and wives in the APIM (Table 5). There was a significant intercept difference for sleep duration indicating that wives slept significantly longer than their husbands. No other significant intercept differences emerged. The actor self-disclosureWP effects among wives were significantly larger than the actor self-disclosureWP effects for men on sleep efficiency and WASO. In contrast, the actor self-disclosureBP effect among husbands was significantly larger than the actor self-disclosureBP effect for wives on WASO.
Table 5. Gender Differences in Actor and Partner Self-disclosure Effects.
Predictor | Subjective sleep quality | Sleep efficiencya | SOLa | WASOa | Sleep duration |
---|---|---|---|---|---|
Intercepts | 0.13 (0.19) | 0.02 (0.05) | -0.02 (0.06) | 0.13 (0.08)† | 0.33(0.12)* |
Actor Effects | |||||
Self-disclosureBP | -0.32 (0.45) | 0.23 (0.13)† | 0.15 (0.15) | 0.44 (0.22)* | -0.03 (0.47) |
Self-disclosureWP | 0.07 (0.06) | -0.03 (0.01)* | -0.03 (0.02)† | -0.06 (0.03)* | 0.06 (0.07) |
Partner Effects | |||||
Self-disclosureBP | 0.51 (0.45) | -0.22 (0.13)† | -0.14 (0.15) | -0.36 (0.22) | 0.09 (0.47) |
Self-disclosureWP | 0.03 (0.06) | -0.01 (0.02) | .00 (0.02) | 0.03 (0.03) | -0.05 (0.07) |
Note. Parameter estimates are unstandardized beta coefficients, with SE in parentheses. n= 38 couples, WP = within-person, BP = between-person, the direction of the difference estimate is wives – husbands, Estimates are unstandardized coefficients.
log10(x+1) transformed variables,
p≤.05,
p<.10.
Alternative Explanations
For both husbands and wives, neither sleep efficiency nor subjective sleep quality the night before predicted the next day's self-disclosure. Dyadic (actor and partner) effects of sleep from both spouses on self-disclosure were not significant (data not shown).4
Discussion
These results are the first to our knowledge to examine the associations between daily self-disclosure and sleep. Emotional self-disclosure predicts health improvements over time (Pennebaker & Chung, 2011) and is related to optimal relationship functioning including increased intimacy (e.g, Laurenceau et al., 1998). On days when wives self-disclosed more than their average, sleep quality and sleep efficiency improved, due to shorter WASO and longer sleep duration. Importantly, these effects remained consistent after adjusting for relationship satisfaction, mood and as revealed in the APIM analysis, after adjusting for partner effects (husbands' self-disclosure). In contrast among husbands, higher average self-disclosure was associated with shorter WASO and this effect remained consistent after adjusting for relationship satisfaction and mood. Further after adjusting for partner effects (wives' self-disclosure) in the APIM analyses, higher average self-disclosure was also associated with better sleep efficiency and shorter SOL. Among wives, but not among husbands, self-disclosure improved sleep on nights when high negative mood was reported. Taken together, these results suggest that while self-disclosure predicted sleep for both husbands and wives, the pattern of how it was associated sleep differed for husbands and wives.
A major strength of this study was the ability to simultaneously test gender differences in the effects of daily variation in self-disclosure and average self-disclosure ratings on sleep using an APIM approach. Consistent with prior research on self-disclosure in marriage (Greene et al., 2006) and based on the person means, husbands and wives did not differ in their average levels of self-disclosure. These results suggest that wives' sleep, particularly sleep efficiency and WASO, is more influenced by daily changes in self-disclosure, while husbands' sleep, particularly WASO, is more influenced by a general tendency to self-disclose to their spouse. The general tendency to self-disclose may be tied to unmeasured personality characteristics that could influence sleep directly or indirectly via relationship functioning. For example, the adult attachment literature suggests that avoidant (insecure) individuals report lower levels of self-disclosure compared to secure individuals (Mikulincer & Nachshon, 1991) and attachment security is associated with better sleep (Scharfe & Eldredge, 2001). Even though experimental studies of the effect of written emotional disclosure on health-related outcomes provide little evidence for gender differences (Epstein, Sloan & Marx, 2005; Sheese, Brown & Graziano, 2004), during interpersonal disclosure gender or factors associated with gender (e.g., social roles) may become important moderators.
Self-disclosure shortened wives' SOL on days when they reported high negative mood. In prior work, higher marital self-disclosure attenuated the negative effects of daily work worries on diurnal cortisol patterns for wives (Slatcher et al., 2010). The present study extends those findings by examining self-disclosure and negative mood at the daily level and their effects on sleep. In other research, greater daily reports of negative mood are associated with lower subjective sleep quality and greater waking during the subsequent night (Akerstedt et al., 2012). Thus, self-disclosure to spouses not only directly influences sleep, but may also buffer the deleterious effects of daily negative mood on sleep. Furthermore, wives' higher than average daily positive mood and self-disclosure independently predicted better subjective sleep quality and sleep efficiency. However, husbands did not benefit from self-disclosure on higher than average negative or positive mood days.
Unexpectedly, greater wives' average self-disclosure ratings were associated with husbands' lower sleep efficiency in the APIM analysis. Currently, it is only possible to speculate about potential mechanisms due to the unknown content and valence of the self-disclosures. Wives high in self-disclosure may be perceived as complaining, over-disclosing or demanding which may lead to negative reactions by husbands during emotional disclosures (e.g., Kleiboer, Kuijer, Hox, Jongen, Frequin, & Bensing, 2007; Zaider, Heimberg & Iida, 2010) . Research on stress crossover in couples (stress in one spouse influencing the other spouse) suggests that husbands might be more susceptible to stress crossover and respond more negatively to stress crossover than wives (Neff & Karney, 2007). For example in another study, wives' higher negative affect during the day predicted greater husbands' cortisol levels approximately 1 to 1 ½ hours later, but the reverse did not occur (Slatcher et. al., 2010). Therefore, high self-disclosing wives may expose their husbands to more negative mood, which may increase husbands' own negative mood and impair sleep.
Of note, participants in this study were “good” sleepers free of sleep disorders such as insomnia. As such, even typically good sleepers report better sleep when they self-disclose to their spouses. Short-lived, infrequent sleep disruptions, such as difficulties falling asleep or staying asleep at least once or twice a week are related to poorer cardiovascular and metabolic health outcomes (e.g., Engeda, Mezuk, Ratliff & Ning, in press). Moreover, good sleepers are still at risk for developing insomnia, and negatively valenced events such as work or interpersonal problems are identified by disturbed sleepers as precipitating factors for insomnia symptoms (Bastien, Vallieres & Morin, 2004) and may sustain sleep disturbances over the long-term (Spielman, 1986). Thus, self-disclosure to spouses may prevent precipitating factors from contributing to and subsequently sustaining sleep problems. Future research should consider the role of self-disclosure to spouses in the context of sleep disorders and sleep-related health conditions (e.g., maternal-fetal health, cardiovascular disease).
Consistent with research on written self-disclosure, merely disclosing thoughts and feelings to a spouse can benefit sleep regardless of content, valence or spousal response. However, unlike written self-disclosure, marital self-disclosure is an interpersonal process. As such, spousal responses to self-disclosure likely play a large role in the extent to which self-disclosure is beneficial (Laurenceau, et al., 2005; Greene et al., 2006). Future research should examine spousal responses to self-disclosure and the self-discloser's perceptions of these responses in both mediating and moderating the association between self-disclosure and sleep. Although it was possible to examine the effect of self-disclosure in the context of positive and negative mood, future research should also examine the content and valence of self-disclosure. How spouses respond to self-disclosure of both positive and negative events influence perceptions of felt security and the availability of spouses to meet disclosers' needs (Collins & Feeney, 2004) and the quality of spousal responses to these different types of disclosure may have consequences for health.
In terms of limitations, the small sample size limited the ability to detect between-person differences in self-disclosure and to adjust for mood and relationship satisfaction in the APIM analyses. Moreover, small sample size plus restricted between-subjects range in sleep outcomes may have contributed to the counterintuitive findings that after accounting for self-disclosure, greater negative mood was related to better sleep (efficiency for wives, subjective sleep quality for husbands). These findings may also not generalize to individuals for whom sleep may be tied to medical problems, such as older adults or patients with chronic illness. Therefore, these findings need replication in larger samples. Additionally after accounting for relationship satisfaction and mood, greater average self-disclosure was associated with husbands' worse sleep quality. It is currently unclear what might explain this effect, and further research is needed to explore potential mechanisms. Self-disclosure was examined in the context of healthy sleepers and might be particularly important for couples dealing with chronic stressors (Hall, Buysse, Nofzinger, Reynolds & Monk, 2008) and disordered sleeping. Thus, the findings may actually understate the potential impact of self-disclosure on sleep and its health consequences. Future work should also examine whether self-disclosure during particular times of the day may be more important for sleep than others. Finally, while self-reported sleep measures are important predictors of health outcomes (e.g., Chandola, Ferrie, Perski, Akbaraly & Marmot, 2010), future research would benefit from including objective sleep measures such as actigraphy and polysomnography.
Sleep is critical to individual health and well-being, and is increasingly recognized as a dyadic experience that is influenced by the quality of couple relationships (Troxel et al., 2007). These findings highlight the importance of relational activities that occur during the day, such as daily self-disclosure to spouses, in affecting sleep generally and protecting bed partners from the detrimental effects of daily negative mood on sleep. Overall, the association between disclosing thoughts and feelings to a significant other and sleep is a potential mechanism that may explain, in part, the association between close relationships and health and well-being.
Acknowledgments
This research was supported by a Research Grant (9333) from the William T. Grant Foundation. Preparation of this manuscript was supported by a postdoctoral fellowship to the first author on MH015750 Biobehavioral Issues in Mental and Physical Health training grant and by a NIH Research Grant (1R01HL114097-01). We would like to thank Gayla Margolin for her contributions to the project, and the graduate students, laboratory staff, and research assistants on the project for their time and effort working with families. We thank the parents and children for their participation in this project.
Footnotes
Despite attempts to screen out mental and selected physical health problems, one wife and one husband reported taking medications to treat anxiety/depression. Two wives reported current medical conditions and 7 wives reported a history of medical conditions potentially associated with impaired sleep. The primary focus of the study was on recruiting children who met inclusion and exclusion criteria; thus, parent screening was less stringent. Therefore, a dummy code for medical conditions (0= not present, 1 = present) was created to see if medical conditions were related to any of the sleep outcomes for wives and husbands. Medical conditions were not related to any sleep outcome for wives (all p's > .28) or husbands (all p's > .45, with the exception of sleep duration p = .18 and its inclusion in the analyses with sleep duration did not alter the results).
Only items pertaining to emotional self-disclosure were included because theoretically and empirically emotional disclosure of thoughts and feelings are stronger predictors of intimacy (Reis & Shaver, 1988; Laurenceau et al., 1998) than disclosure of facts, and written self-disclosure paradigms utilize writing thoughts and feelings about traumatic events.
Diary studies complicate traditional approaches to reliability because of the small number of items per construct, and the repeated administrations over time. Shrout and Lane (2012) recently described a framework based on generalizability theory for quantifying reliability in diary studies. Two estimates are relevant for this paper. First, the reliability of average ratings from all items and all days, which addresses how well the particular scale can differentiate between person differences, was excellent across all the diary measures in the study (.99 – 1.00 in all cases) and was thus not reported for each scale. Second, the reliability of day-to-day change, which addresses how well the particular scale can estimate within-person differences, is described for each scale with the notation Rc.
Results are available from the first author upon request.
Contributor Information
Heidi S. Kane, Wayne State University.
Richard B. Slatcher, Wayne State University
Bridget M. Reynolds, University of California Los Angeles
Rena L. Repetti, University of California Los Angeles
Theodore F. Robles, University of California Los Angeles
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