Sex Differences in Sleep Behaviors in Military Health System

Background: Sex differences in sleep-related behavior and beliefs in the military have not been well described. Methods: This study examined sex differences in sleep-related patterns, behavior, and beliefs among 270 participants, aged 18 to 75 years, who were referred for sleep concerns at 2 Military Health System facilities. Following a baseline assessment, participants wore a commercial sleep tracker (Fitbit Inspire 2) during a 10-day assessment period and completed daily sleep diaries and twice daily symptom surveys via smartphone. Results: Relative to males, females experienced poorer subjective and objective sleep and reported more frequent maladaptive presleep behaviors and beliefs. Objective monitoring revealed that females recorded longer total sleep time than males. However, females reported significantly worse subjective sleep continuity, characterized by taking longer to fall asleep, experiencing more nighttime awakenings, and having lower overall sleep efficiency. Females also reported higher levels of bedtime stress and negative emotion, more frequent presleep cognitive arousal and racing thoughts, the recurrent belief of needing 8 hours of sleep to feel refreshed and alert, and a greater tendency to remain in bed longer than intended. Conclusions: This study underscores the importance of recognizing sex-based differences in sleep patterns, behaviors, and beliefs to guide personalized care. Personalized care and incorporating cognitive behavioral techniques may be effective for addressing these differences in women. Telehealth could expand access to such treatments, particularly within the Military Health System.Sex differences in sleep medicine are well documented. Research has found sex-based variations in sleep patterns, daytime symptoms, and prevalence of common sleep disorders, as well as response to treatment.[1-3] Relative to men, women in the general population are 1.5 times more likely to experience insomnia, which also has been observed in military populations.[4,5] These differences underscore the importance of considering sex-specific factors in sleep medicine clinical care. Despite this, research examining differences in sleep-related behavior and beliefs between men and women is scarce. From a clinical perspective, such insight is needed to guide personalized treatment planning and maximize patient-centered outcomes. This study sought to compare sleep patterns, behavior, and beliefs between males and females. We hypothesized that these sleep outcomes differ by sex.MethodsData were gathered as part of a larger study of sleep telehealth in the US military. The research methods have been previously published.[6] Briefly, active-duty military service members and Defense Eligibility Enrollment Reporting System beneficiaries aged 18 to 75 years were recruited from Walter Reed National Military Medical Center and the Alexander T. Augusta Military Medical Center. Participants owned a smartphone and were clinician- or self-referred for sleep problems. Exclusion criteria included pregnancy, uncontrolled medical or psychiatric illness, pending retirement, or permanent change of station. Participants completed sleep and health questionnaires during a baseline assessment. Self-reported sleep behavior and beliefs were assessed using 5-point Likert scale (1, never; 5, almost always). Next, during a 10-day monitoring period, participants wore a commercial Fitbit Inspire 2 sleep tracker and completed daily sleep diaries. Likert scale daytime symptom assessments (ie, evaluated in a “I feel ___” format to assess cognition [alert, clear-headed], energy level [refreshed, fatigued], and mood [happy, sad, stressed, relaxed]) were completed twice daily on the smartphone.[6,7]To test the hypothesis that sleep behavior and beliefs differ between males and females, between-groups differences were evaluated in subjective (diary) and objective (wearable) sleep, and self-reported sleep schedule, presleep behaviors, bedroom environment, sleep thinking, and motivation to change. F-statistics and P values were derived from linear models after adjusting for depression (ie, Patient Health Questionnaire-9 score), anxiety (ie, Generalized Anxiety Disorder-7 score), age, and race. Given the large number of statistical comparisons, P values were adjusted using the Benjamini–Hochberg procedure.ResultsA total of 270 individuals with a mean (SD) age of 45.8 (13.0) years participated in the study; 149 (55.2%) were male. Participants self-identified as White (56.3%), Black (23.7%), Hispanic (8.5%), or Asian (7.0%). Participants included 126 active duty (46.7%), 74 retired military (27.4%), 67 civilian beneficiaries (24.8%), and 3 activated reserve or national guard (1.1%).Females reported longer mean (SD) sleep onset latency compared with males (35.2 [26.0] vs 24.4 [18.6] minutes; P < .001), increased mean (SD) wake after sleep onset (26.1 [23.2] vs 19.2 [19.0] minutes; P = .01), and lower mean (SD) sleep efficiency (82.0% [9.0] vs 87.0% [7.0]; P < .001). Although no differences were observed between males and females in mean (SD) self-reported total sleep time (6.8 [1.2] vs 6.5 [1.0] hours; P = 11), objective mean (SD) total sleep time was longer for females vs males (6.4 [1.0] vs 5.9 [1.1] hours; P < .001) (Table). Compared with males, females reported a higher mean (SD) number of times they went to bed “feeling stressed, angry, or upset” (1.6 [0.9] vs 1.4 [0.8]; P = .03). Females reported excessive mean (SD) time in bed more often than males (1.8 [1.1] vs 1.4 [0.9]; P = .03). Females had higher mean (SD) rate of endorsing “my thoughts overwhelm me at night, and I am unable to control my racing mind” compared with males (2.0 [1.1] vs 1.6 [1.1]; P = .03). Females had a more frequent mean (SD) belief that “I need 8 hours of sleep to feel refreshed and alert” compared with males (2.6 [1.2] vs 2.0 [1.1]; P < .001). DiscussionThis study found that females were more likely to have maladaptive sleep behaviors and thinking compared with males. Females reported they were more likely to believe that 8 hours of sleep is needed to feel refreshed and alert, have thoughts that overwhelm at night and a racing mind, go to bed feeling stressed, angry, or upset, and stay in bed longer than recommended. Therefore, females appear to be at higher risk for proarousal behavior and beliefs that reinforce an association between wakefulness and the bed and may worsen trouble falling and staying asleep. This is consistent with subjective sleep schedule findings as females were more likely to self-report longer sleep onset latency, greater wake after sleep onset, and lower sleep efficiency compared with males.[8,9] Our findings demonstrate a notable discrepancy between self-reported and objectively measured total sleep time. While males and females perceived their sleep duration similarly, objective data revealed a significant sex difference—females exhibited a longer average total sleep duration. This highlights a potential sex-specific bias in self-perceived sleep duration, particularly for females who may underestimate their actual sleep time.Our findings build upon and expand prior literature. Significant sex differences in proarousal behaviors prior to bed, total time in bed, and delayed onset of sleep have been found previously.[9] Sidani et al found that women reported a greater perception of insomnia severity and more worry about bedtime compared with men.[1] Anxious traits such as neuroticism have been identified to be common in women.[10] In combination with perceived stress and worry about bedtime, these beliefs may contribute to anxious feelings and hyperarousal prior to bed that prolongs sleep latency and/or wake after sleep onset.[1] Hantsoo et al found that higher presleep arousal in women was associated with possessing more negative emotion.[11] However, sleep cognition and behaviors are complex and many factors may contribute to their development over time. For example, differences in cultural norms and expectations for child-rearing (ie, nighttime feedings and awakenings) and hormonal fluctuations throughout the menstrual cycle and postmenopause have the potential to also influence these relationships.[12]Strengths and LimitationsThe use of an objective measure of sleep over a 10-day period, during which participants could remain in familiar surroundings while maintaining their normal routines was a strength of this study. This ecological approach provided a robust snapshot of typical sleep patterns as well as behaviors and beliefs. At the same time, our sample was not randomly selected and did not control for specific sleep conditions and medications. It is unclear how well our results will generalize to other populations, such as civilians or individuals from other geographic regions. There may be unique factors among military members and beneficiaries that contribute to poor sleep.[13]These findings suggest notable sex differences in sleep patterns, behaviors and beliefs, which are potential targets for personalized interventions that could improve sleep medicine outcomes. Because females reported more frequent negative thinking and behaviors related to sleep, they may positively respond to interventions that target related behaviors and beliefs, such as incorporating stimulus control techniques. Supporting this hypothesis, a retrospective chart review by Scott et al found that women with insomnia experience a greater reduction in fatigue and improved functioning after receiving treatment with cognitive behavioral therapy for insomnia.[14] ConclusionsWe observed important differences between men and women in sleep patterns, behavior, and beliefs. Given increased recognition of the importance of women’s sleep health,[15] these data highlight the importance of personalized and patient-centered care to improve outcomes in sleep medicine.