Sleep EEG, depression and gender

Sex Differences in Temporal Sleep Patterns, Social Jetlag, and Attention in High School Adolescents

Insufficient sleep and irregular sleep hours are common in adolescents, who experience a delayed sleep phase due to biopsychosocial changes associated with puberty, resulting in later sleep times. However, early morning class hours shorten sleep duration on weekdays. This condition is harmful to cognitive performance, which may be accentuated in girls due to a greater sleep need and less resistance to sleep deprivation. In this study, we evaluated sex differences concerning temporal sleep patterns, social jetlag, and attention in high school adolescents attending morning classes. Students ( n  = 146 - F: 73-16.1 ± 0.8 years; M: 73-16.2 ± 0.9 years) completed a Health and Sleep questionnaire, kept a sleep diary for 10 days, which incorporated a Maldonado Sleepiness Scale, and performed a Continuous Performance Task. Girls went to bed earlier and woke up on weekends, and spent more time in bed at night and in 24 h on weekdays and weekends, while they also had a greater irregularity in wake-up times ( p  < 0.05). There were no differences between sexes in terms of social jetlag, sleep debt, and sleepiness upon awakening ( p  > 0.05). Regarding attention, the girls had a longer reaction time in phasic alertness ( p  < 0.01) and a tendency to have fewer errors in selective attention ( p  = 0.06). These results persisted when controlled for sleep parameters. Therefore, we suggest that girls have a greater sleep need and less resistance to sleep deprivation, while the differences in attention performance could be due to different strategies, the girls could be making a trade, increasing reaction time in favor of better accuracy, while the boys could be prioritizing a faster response time.

Sleep quality in relation to perceived psychological stress in patients with type 2 diabetes and in age- and sex-matched control individuals

AIM

To assess sleep quality in relation to perceived stress in patients with type 2 diabetes (T2DM) and age- and sex-matched controls.

METHODS

Perceived stress level and sleep quality assessed in 154 patients with T2DM (58 men, 96 women, age 58.3 ± 11.9 years), 154 matched controls (58 men, 96 women, age 56.8 ± 12.2 years) using Perceived Stress Scale and Pittsburgh Sleep Quality Index.

RESULTS

Patients with T2DM had worse subjective sleep quality (p < 0.001), sleep latency (p = 0.047) than controls. Patients with high stress level had worse subjective sleep quality (p = 0.027), higher use of sleeping medication (p = 0.023), daytime dysfunction (p < 0.001) than those with low stress level. No significant differences in sleep quality between controls with high and low perceived stress level. Perceived stress level in patients with T2DM correlated with subjective sleep quality (r = 0.260, p = 0.002), sleep duration (r = 0.228, p = 0.005), use of sleep medication (r = 0.245, p = 0.004), daytime dysfunction (r = 0.326, p < 0.001), in age- and sex-matched controls-to daytime dysfunction (r = 0.191, p = 0.037).

CONCLUSION

Sleep quality (subjective sleep quality, sleep latency) is worse in patients with type 2 diabetes than in age- and sex-matched controls. Patients with high perceived stress level have worse subjective sleep quality, higher use of sleeping medication, daytime dysfunction than patients with low perceived stress level; no significant differences in sleep quality between controls with high and low stress level. Perceived stress level in patients with type 2 diabetes is related to subjective sleep quality, sleep duration, use of sleep medication, daytime dysfunction, in age- and sex-matched controls-to daytime dysfunction.

Fundamentals of sleep regulation: Model and benchmark values for fractal and oscillatory neurodynamics

Homeostatic, circadian and ultradian mechanisms play crucial roles in the regulation of sleep. Evidence suggests that ratios of low-to-high frequency power in the electroencephalogram (EEG) spectrum indicate the instantaneous level of sleep pressure, influenced by factors such as individual sleep-wake history, current sleep stage, age-related differences and brain topography characteristics. These effects are well captured and reflected in the spectral exponent, a composite measure of the constant low-to-high frequency ratio in the periodogram, which is scale-free and exhibits lower interindividual variability compared to slow wave activity, potentially serving as a suitable standardization and reference measure. Here we propose an index of sleep homeostasis based on the spectral exponent, reflecting the level of membrane hyperpolarization and/or network bistability in the central nervous system in humans. In addition, we advance the idea that the U-shaped overnight deceleration of oscillatory slow and fast sleep spindle frequencies marks the biological night, providing somnologists with an EEG-index of circadian sleep regulation. Evidence supporting this assertion comes from studies based on sleep replacement, forced desynchrony protocols and high-resolution analyses of sleep spindles. Finally, ultradian sleep regulatory mechanisms are indicated by the recurrent, abrupt shifts in dominant oscillatory frequencies, with spindle ranges signifying non-rapid eye movement and non-spindle oscillations - rapid eye movement phases of the sleep cycles. Reconsidering the indicators of fundamental sleep regulatory processes in the framework of the new Fractal and Oscillatory Adjustment Model (FOAM) offers an appealing opportunity to bridge the gap between the two-process model of sleep regulation and clinical somnology.

Exploring Convolutional Neural Network Architectures for EEG Feature Extraction

The main purpose of this paper is to provide information on how to create a convolutional neural network (CNN) for extracting features from EEG signals. Our task was to understand the primary aspects of creating and fine-tuning CNNs for various application scenarios. We considered the characteristics of EEG signals, coupled with an exploration of various signal processing and data preparation techniques. These techniques include noise reduction, filtering, encoding, decoding, and dimension reduction, among others. In addition, we conduct an in-depth analysis of well-known CNN architectures, categorizing them into four distinct groups: standard implementation, recurrent convolutional, decoder architecture, and combined architecture. This paper further offers a comprehensive evaluation of these architectures, covering accuracy metrics, hyperparameters, and an appendix that contains a table outlining the parameters of commonly used CNN architectures for feature extraction from EEG signals.

Physical activity and morningness: A helpful combination in improving the sleep quality of active Italian university students

University students are commonly described as having worsened sleep quality, especially when inactive and Evening-type (E-type) subjects. This study aimed to examine the interactions between physical activity and chronotype on sleep quality among a sample of active Sports Science university students. In November 2019, 433 participants (mean age: 19.7 ± 1.56 years; 70% males) completed the Pittsburgh Sleep Quality Index, the Godin-Shepard Leisure-Time Physical Activity Questionnaire (tertiles categorisation), and the Morningness-Eveningness Questionnaire. Females and E-type slept significantly worse than males and Neither-(N-types) and Morning-types (M-types), respectively. However, there were no significant differences in sleep quality based on physical activity levels. The three-way ANOVA revealed that sleep quality in N- and E-types appeared to be independent of physical activity, whereas M-types showed an improvement in sleep classification with increased physical activity. Moderation analysis indicated that physical activity significantly moderated the relationship between chronotypes and sleep quality. Specifically, M-types demonstrated a more pronounced improvement in sleep quality with increasing physical activity compared to the other chronotypes. In conclusion, M-type university students derived the greatest benefits from physical activity in improving sleep quality. Conversely, physical activity seemed to have a limited impact on sleep quality among active E-type university students.

The stress of losing sleep: Sex-specific neurobiological outcomes

Sleep is a vital and evolutionarily conserved process, critical to daily functioning and homeostatic balance. Losing sleep is inherently stressful and leads to numerous detrimental physiological outcomes. Despite sleep disturbances affecting everyone, women and female rodents are often excluded or underrepresented in clinical and pre-clinical studies. Advancing our understanding of the role of biological sex in the responses to sleep loss stands to greatly improve our ability to understand and treat health consequences of insufficient sleep. As such, this review discusses sex differences in response to sleep deprivation, with a focus on the sympathetic nervous system stress response and activation of the hypothalamic-pituitary-adrenal (HPA) axis. We review sex differences in several stress-related consequences of sleep loss, including inflammation, learning and memory deficits, and mood related changes. Focusing on women's health, we discuss the effects of sleep deprivation during the peripartum period. In closing, we present neurobiological mechanisms, including the contribution of sex hormones, orexins, circadian timing systems, and astrocytic neuromodulation, that may underlie potential sex differences in sleep deprivation responses.

Novel methods for elucidating modality importance in multimodal electrophysiology classifiers

Introduction

Multimodal classification is increasingly common in electrophysiology studies. Many studies use deep learning classifiers with raw time-series data, which makes explainability difficult, and has resulted in relatively few studies applying explainability methods. This is concerning because explainability is vital to the development and implementation of clinical classifiers. As such, new multimodal explainability methods are needed.

Methods

In this study, we train a convolutional neural network for automated sleep stage classification with electroencephalogram (EEG), electrooculogram, and electromyogram data. We then present a global explainability approach that is uniquely adapted for electrophysiology analysis and compare it to an existing approach. We present the first two local multimodal explainability approaches. We look for subject-level differences in the local explanations that are obscured by global methods and look for relationships between the explanations and clinical and demographic variables in a novel analysis.

Results

We find a high level of agreement between methods. We find that EEG is globally the most important modality for most sleep stages and that subject-level differences in importance arise in local explanations that are not captured in global explanations. We further show that sex, followed by medication and age, had significant effects upon the patterns learned by the classifier.

Discussion

Our novel methods enhance explainability for the growing field of multimodal electrophysiology classification, provide avenues for the advancement of personalized medicine, yield unique insights into the effects of demographic and clinical variables upon classifiers, and help pave the way for the implementation of multimodal electrophysiology clinical classifiers.

Compared with Him or Her, I Am Not Good Enough: How to Alleviate Depression Due to Upward Social Comparison?

The present study primarily aims to examine the mediating role of core self-evaluation and the moderating role of personal growth initiative (PGI) in the relationship between upward social comparison and senior high school students' depression and to explore the gender difference in this association. A total of 721 Chinese senior high school students (61.16% boys; M = 16.21 years, SD = 1.07) completed measures of upward social comparison, core self-evaluation, personal growth initiative, and depression. Results showed a significant positive correlation between upward social comparison and depression. Core self-evaluation partially mediated this association, and a gender difference in the indirect effect was revealed; that is, the effect was shown to be stronger for girls than for boys. Moreover, for boys, the mediating effect of core self-evaluation was moderated by PGI, and the effect was more potent for individuals with high PGI than for those with low PGI. However, no moderating effect of PGI on the indirect effect was found for girls. These findings suggest that prevention and interventions focusing on reducing upward social comparison and enhancing core self-evaluation may alleviate adolescents' depression symptoms and that more attention should be given to girls with low core self-evaluation and boys with high PGI.

Do Sleep Disturbances Improve Following Psychoanalytic Psychotherapy for Adolescent Depression?

Sleep disturbance is often a prominent symptom in adolescents diagnosed with major depressive disorder (MDD). Recent evidence indicates that short-term psychoanalytic psychotherapy (STPP) for depression may have an effect in reducing co-occurring sleep disturbance in youth. It is unknown if transference work (exploration of the patient–therapist relationship) has an additional effect in reducing sleep disturbance. Adolescents aged 16–18 years (n = 69, 84% female) who met diagnostic criteria for MDD based on the Mini International Neuropsychiatric Interview (M.I.N.I) were randomized to either STPP with transference work or without. Sleep problems were assessed at baseline, therapy session 20 (20 weeks), post-treatment (28 weeks), and one-year follow-up (80 weeks) with the Symptom Checklist-90-R. At baseline, 69% of the adolescents exhibited moderately to extreme sleep difficulties. Sleep disturbance was significantly correlated to depression depth at session 20 and at follow-up. Symptoms of insomnia significantly decreased from baseline to the end of treatment. Treatment gains were maintained until follow-up. No differences in recovery of sleep disturbance were found between the two treatment groups. The findings suggest that sleep disturbance improves following STPP for depression, with or without transference work. Future research should assess those with residual symptoms by different sleep measures.

Association between social capital and sleep duration among rural older adults in China

OBJECTIVE

Sleep disturbances are great challenges to older adults' health promotion. The study tested gender differences in the association between different dimensions of social capital and self-reported sleep duration of Chinese rural older adults.

DESIGN

The data of rural older adults were extracted from a national cross-sectional survey of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) and analyzed in this study.

SETTING

CLHLS covered 23 provinces in China.

PARTICIPANTS

The 6552 rural respondents aged ≥65 years old were involved.

MAIN OUTCOME MEASURES

Generalized trust, informal social participation, formal social participation and social support were used to assess social capital. Self-reported sleep duration was measured as health outcome.

RESULTS

Low level of generalized trust had harmful effect on insufficient sleep (AOR 1.110, 95% CI 1.018-1.324), and having no formal or informal social participation was significantly positively associated with long sleep (AOR_formal 1.424, 95% CI 1.007-2.013; AOR_informal 1.241, 95% CI 1.016-1.516). Rural older female adults with no emotional social support had higher odds of insufficient sleep (AOR 1.502, 95% CI 1.258-1.978). Meanwhile, both informal and formal social participation showed inverse association with long sleep for females.

CONCLUSIONS

This study found the relationship between social capital, sleep duration and the gender differences in Chinese rural older adults. More targeted sleep disturbance interventions could be taken in social capital of rural older adults, and gender differences should be considered when making social capital-embedded health promotion policies and interventions.

When Non-Suicidal Self-Injury Predicts Non-Suicidal Self-Injury and Poor Sleep-Results from a Larger Cross-Sectional and Quasi-Longitudinal Study

Poor sleep is associated with a higher risk of non-suicidal self-injury (NSSI) as a proxy of unfavorable emotion regulation. In the present study, we tested the hypothesis that past non-suicidal self-injury was associated with current non-suicidal self-injury and with current subjective sleep patterns. To this end, a larger sample of young adults were assessed. A total of 2374 adults (mean age: 27.58 years; 39.6% females) completed a series of self-rating questionnaires covering sociodemographic information, past and current NSSIs, suicide attempts, and current sleep patterns, including experiencing nightmares. Past NSSIs predicted current NSSIs. Current sleep patterns had a modest impact on the association between past and current NSSIs. Compared to male participants, female participants did not report more sleep complaints or more current NSSIs, but more past NSSIs. Past NSSIs predicted the occurrences of nightmares and suicide attempts. The best predictor of current NSSI was the remembered past NSSI, while current poor sleep was only modestly associated with current NSSI. Further indicators of current NSSI and poor sleep were suicide attempts and nightmares within the last six months. Overall, it appears that poor emotion regulation should be considered as underlying factor to trigger and maintain non-suicidal self-injury-related behavior and poor sleep. Further, unlike previous studies, which focused on the possible influence of sleep patterns on NSSIs, the aim of the present study paradigm was to investigate NSSIs on sleep patterns.

Compounding Effects of Traumatic Brain Injury, Military Status, and Other Factors on Pittsburgh Sleep Quality Index: A Meta-analysis

INTRODUCTION

Traumatic brain injury (TBI) or concussion is a known risk factor for multiple adverse health outcomes, including disturbed sleep. Although prior studies show adverse effects of TBI on sleep quality, its compounding effect with other factors on sleep is unknown. This meta-analysis aimed to quantify the effects of TBI on subjective sleep quality in the context of military status and other demographic factors.

MATERIALS AND METHODS

A programmatic search of PubMed database from inception to June 2020 was conducted to identify studies that compared subjective sleep quality measured using Pittsburgh Sleep Quality Index (PSQI) in individuals with TBI relative to a control group. The meta-analysis included group-wise standard mean difference (SMD) and 95% CI. Pooled means and SDs were obtained for TBI and non-TBI groups with and without military service, and meta-regression was conducted to test for group effects. Exploratory analysis was performed to test for the effect of TBI, non-head injury, military status, sex, and age on sleep quality across studies.

RESULTS

Twenty-six articles were included, resulting in a combined total of 5,366 individuals (2,387 TBI and 2,979 controls). Overall, individuals with TBI self-reported poorer sleep quality compared to controls (SMD = 0.63, 95% CI: 0.45 to 0.80). Subgroup analysis revealed differences in the overall effect of TBI on PSQI, with a large effect observed in the civilian subgroup (SMD: 0.80, 95% CI: 0.57 to 1.03) and a medium effect in the civilian subgroup with orthopedic injuries (SMD: 0.40, 95% CI: 0.13 to 0.65) and military/veteran subgroup (SMD: 0.43, 95% CI: 0.14 to 0.71). Exploratory analysis revealed that age and history of military service significantly impacted global PSQI scores.

CONCLUSIONS

Poor sleep quality in TBI cohorts may be due to the influence of multiple factors. Military/veteran samples had poorer sleep quality compared to civilians even in the absence of TBI, possibly reflecting unique stressors associated with prior military experiences and the sequelae of these stressors or other physical and/or psychological traumas that combine to heightened vulnerability. These findings suggest that military service members and veterans with TBI are particularly at a higher risk of poor sleep and its associated adverse health outcomes. Additional research is needed to identify potential exposures that may further heighten vulnerability toward poorer sleep quality in those with TBI across both civilian and military/veteran populations.

Sex differences in the factors associated with sleep duration in university students: A cross-sectional study

BACKGROUND

Insufficient sleep duration among university students was commonly associated with many detrimental effects. University students experience substantial environmental and psychological changes. Female and male university students may differ in many spheres. However, most research on sleep duration of university students is based on an aggregate sample rather than digging the sex-specific profiles. The objective of this study is to examine potential sex differences in the correlates of sleep duration and explore the underlying mechanism of correlations.

METHODS

This is a large-scale university-based mental health survey, which was conducted in university students in Qinghai Province in Northwest China in December 2019. A multi-stage logistic regression was separately fitted by sex to examine the factors associated with short sleep duration in university students.

RESULTS

A total of 5,552 university students with an average sleep duration of 6.88 h (SD = 1.04) were included, among which 35.0% of the participants may currently be sleeping less than the optimal duration. Female students (6.84 h, SD = 1.00) slept shorter than males (6.94 h, SD = 1.09). The only parallel between sexes was that both female and male students with 3-5 times weekly breakfast were less likely to have short sleep duration. Adjusting for depressive symptoms in the following step eliminated the association between anxiety symptoms and short sleep duration in the model for female students. Female-specific associated factors with short sleep duration were age, grade, academic pressure, weekly physical exercise, depressive symptoms. Male-specific characteristics were current smoking tobacco cigarette, self-perceived health, duration of daily Internet use.

CONCLUSION

Characteristic profiles of sleep duration differed between female and male university students; only a few male-specific factors were identified. Psychological guidance and education courses as well as other interventions to improve university students' sleep and related health should be designed and implemented based on sex differences.

Sleep disorders and depression due to menopausal symptoms in middle-aged Korean females

[Purpose] The purpose of this study was to identify the differences in the incidence of sleep disorders and depression in postmenopausal middle-aged females in South Korea. [Participants and Methods] This study was a cross-sectional study. A total of 87 middle-aged females between the ages of 40 and 60 years were selected through convenience sampling. The data were collected with a self-reported questionnaire from May 1 to May 29, 2017. [Results] The mean menopause score of the study was 5.37. The menopause symptoms indicated significant differences in sexual life. The association between the incidence of menopausal symptoms and sleep disorders and depression scores based on a scale of 1 to 10 was analyzed. Menopausal symptoms strongly affected sleep and depression in middle-aged females. [Conclusion] The findings of this study may be useful in understanding depression and sleep disorders in middle-aged females and for developing more specific programs for depression and sleep disorders. Management strategies are also needed.

Differences in sleep measures and waking electroencephalography of patients with insomnia according to age and sex

STUDY OBJECTIVES

Sleep characteristics are known to be different according to age and sex. The objective of this study was to investigate differences in sleep parameters and quantitative electroencephalography of patients with insomnia according to age and sex.

METHODS

Patients with insomnia disorder ages 40-79 years were recruited. Each participant was assessed with the Pittsburgh Sleep Quality Index, 4-day wrist actigraphy, and quantitative electroencephalography derived from a 64-channel electroencephalogram system. These variables were compared between age groups (40-64 years vs 65-79 years) and sexes.

RESULTS

Among 173 participants, 61 (35%) were ages 65-79 years and 64 (35%) were males. The older group reported shorter (P = .009) total sleep time than the middle-aged group based on the Pittsburgh Sleep Quality Index, while women slept longer than men based on actigraphy (P = .040). Regarding electroencephalography, women had higher relative beta power than men (P = .006). Older patients showed slower dominant occipital frequency than younger patients (P = .008). The age effect was more noticeable on both clinical variables and quantitative electroencephalography for women. Compared with younger women, older women reported shorter total sleep time in the Pittsburgh Sleep Quality Index (P = .025), underestimated their sleep time (Pittsburgh Sleep Quality Index total sleep time/actigraphic total sleep time, P = .034), and showed reduced alpha power in the frontal area (P = .009).

CONCLUSIONS

Clinicians should be aware of the age and sex difference on manifestation of insomnia, which may further impact an individual's behaviors, such as staying in bed for a longer time or seeking sleep aids.

Perceived stress and sleep quality among the non-diseased general public in China during the 2019 coronavirus disease: a moderated mediation model

BACKGROUND

The 2019 coronavirus disease (COVID-19) has spread worldwide, and its associated stressors have resulted in decreased sleep quality among front-line workers. However, in China, the general public displayed more psychological problems than the front-line workers during the pandemic. Therefore, we investigated the influence of perceived stress on the sleep quality of the non-diseased general public and developed a moderated mediation model to explain said relationship.

METHODS

Questionnaire-based surveys were conducted online from February 18-25, 2020 with 1630 Chinese participants (aged 18-68 years).

RESULTS

Around one-third (36.38%) of participants were poor sleepers during the COVID-19 pandemic. Moreover, higher perceived stress was significantly associated with higher anxiety levels, which, in turn, was associated with lower sleep quality. Self-esteem moderated the indirect effect of perceived stress on sleep quality through its moderation of the effect of perceived stress on anxiety. This indicated that the mediation effect of anxiety was stronger in those with low levels of self-esteem than in those with high levels of self-esteem.

CONCLUSIONS

These findings suggest that both the sleep quality and perceived stress levels of the non-diseased general public required attention during the COVID-19 pandemic. Our findings also identify personality characteristics related to better sleep quality, demonstrating the important role of self-esteem in environmental adaptation.

Elucidating the Relationship Between Insomnia, Sex, and Cardiovascular Disease

Sex differences in cardiovascular disease (CVD) mortality have been attributed to differences in pathophysiology between men and women and to disparities in CVD management that disproportionately affect women compared to men. Similarly, there has been investigation of differences in the prevalence and presentation of insomnia attributable to sex. Few studies have examined how sex and insomnia interact to influence CVD outcomes, however. In this review, we summarize the literature on sex-specific differences in the prevalence and presentation of insomnia as well as existing research regarding the relationship between insomnia and CVD outcomes as it pertains to sex. Research to date indicate that women are more likely to have insomnia than men, and there appear to be differential associations in the relation between insomnia and CVD by sex. We posit potential mechanisms of the relationship between sex, insomnia and CVD, discuss gaps in the existing literature, and provide commentary on future research needed in this area. Unraveling the complex relations between sex, insomnia, and CVD may help to explain sex-specific differences in CVD, and identify sex-specific strategies for promotion of cardiovascular health. Throughout this review, terms “men” and “women” are used as they are in the source literature, which does not differentiate between sex and gender. The implications of this are also discussed.

The effect of sleep on the salivary cortisol response to acute stressors: a review and suggestions

There have been steadily increasing studies on the relationship between sleep and stress. However, the findings regarding the effects of sleep on the acute stress response have been inconsistent. Elevated, blunted, or unchanged salivary cortisol stress response have been reported. Therefore, this study conducted a systematic review of previous studies to provide a comprehensive summary of the factors that influence the effects of sleep on the salivary cortisol stress response. We conducted a comprehensive electronic literature search in PubMed, PsycINFO, PsycARTICLES, Web of Science, MEDLINE, and EMBASE for human studies published in English (up to June 2019). Finally, 17 articles with participants aged 6.4-72 years were included in this review. We assessed the following factors: designing factors (sleep measurement, stress induction, cortisol sampling period, and time intervals between sleep measurement and the acute stress task), analyzing factors (cortisol analysis), and participants' characteristics (age, sex, and background stress levels); subsequently, we explained conflicting findings across the current literature. Further, we provide study design, analysis, and report suggestions for optimal assessment of the effects of sleep on the acute stress response. This summary of influencing factors and suggestions for future studies could help elucidate the impact of sleep on stress and advance the field.

Gender differences in adolescent sleep neurophysiology: a high-density sleep EEG study

During adolescence, differences between males and females in physiology, behavior and risk for psychopathology are accentuated. The goal of the current study was to examine gender differences in sleep neurophysiology using high-density sleep EEG in early adolescence. We examined gender differences in sleep EEG power and coherence across frequency bands for both NREM and REM sleep in a sample of 61 adolescents (31 girls and 30 boys; mean age = 12.48; SD = 1.34). In addition, sleep spindles were individually detected and characterized. Compared to boys, girls had significantly greater spindle activity, as reflected in higher NREM sigma power, spindle amplitude, spindle frequency and spindle density over widespread regions. Furthermore, power in higher frequency bands (16.2–44 Hz) was larger in girls than boys in a state independent manner. Oscillatory activity across frequency bands and sleep states was generally more coherent in females as compared to males, suggesting greater connectivity in females. An exception to this finding was the alpha band during NREM and REM sleep, where coherence was higher (NREM) or not different (REM) in boys compared to girls. Sleep spindles are generated through thalamocortical circuits, and thus, the greater spindle activity across regions in females may represent a stronger thalamocortical circuit in adolescent females as compared to males. Moreover, greater global connectivity in females may reflect functional brain differences with implications for cognition and mental health. Given the pronounced gender differences, our study highlights the importance of taking gender into account when designing and interpreting studies of sleep neurophysiology.

Emotional exhaustion and sleep-related worry as serial mediators between sleep disturbance and depressive symptoms in student nurses: A longitudinal analysis

OBJECTIVE

The multi-wave longitudinal study was to explore the underlying mechanisms between sleep disturbance and depressive symptoms for up to 9.5 months among student nurses and to examine whether emotional exhaustion and sleep-related worry could be the mediators.

METHODS

856 student nurses aged 15-24 years (mean age = 17.8 years; all female) were recruited from a nursing school. Participants reported demographic variables (age, sibling, location, health condition, family monthly income and parents' marital quality) at baseline (Time1), Body Mass Index, weekly exercise, sleep disturbance and depressive symptoms at 3-month into internship (Time2), emotional exhaustion and sleep-related worry at 6-month into internship (Time3), and depressive symptoms at 9.5-month follow-up (Time4). Mediation analyses with bootstrapping were conducted to investigate the mediating role of emotional exhaustion and sleep-related worry in the relationship between sleep disturbance and depressive symptoms.

RESULTS

Adjusted analyses suggested that the direct effect of sleep disturbance on depressive symptoms was not significant (β = 0.026, SE = 0.069, p = .71). Mediation analyses revealed two significant indirect effects between Time2 sleep disturbance and Time4 depressive symptoms with the mediating effect of emotional exhaustion (β = 0.019, SE = 0.009, BC95%CI [0.0036,0.0405]) and sleep-related worry (β = 0.016, SE = 0.008, BC95%CI [0.0026,0.0337]) respectively. When testing serial multiple mediation, the specific indirect effect of sleep disturbance on depressive symptoms through both emotional exhaustion and sleep-related worry was significant (β = 0.005, SE = 0.003, BC95%CI [0.0004,0.0123]).

CONCLUSIONS

Emotional exhaustion and sleep-related worry were positively associated with sleep disturbance and depressive symptoms.

Bedtime Procrastination, Sleep-Related Behaviors, and Demographic Factors in an Online Survey on a Polish Sample

The sufficient length and good quality of night sleep play a vital role in maintaining health, well-being and effective functioning. Nevertheless, an increase in the prevalence of sleep deprivation can be observed recently. The concept of bedtime procrastination, defined as going to bed later than intended, has been proposed to explain one of the psychological determinants of sleep deficiency. To investigate the prevalence of bedtime procrastination among Poles we carried out a Polish adaptation of the Bedtime Procrastination Scale (BPS), a self-report questionnaire for measuring the tendency to voluntarily postpone going to bed in the absence of any external circumstances for doing so. The aim of the research was to determine the main psychometric properties of the Polish version of the BPS. We also aimed to identify the relationships between bedtime procrastination and selected demographic variables in the Polish sample, and to examine the impact of bedtime procrastination on self-reported sleep outcomes. The data obtained from online surveys conducted on two Polish samples were analyzed, including demographic factors, self-reported sleep outcomes, and responses to items of the BPS. The Polish version of the BPS has a unifactorial structure like the original version. It also exhibits satisfactory internal consistency and moderate temporal stability in a 10-week retest study. BPS scores were not significantly related to the place of residence, the highest completed level of education, living with a spouse or partner, and living with children. Scores in BPS slightly decreased with age and females scored higher on BPS than males. Higher BPS scores were obtained for a group of students in comparison to a group of subjects who were not students, and lower BPS scores were found in working respondents in comparison to respondents who were not working. BPS scores correlate negatively with sleep length on workdays and a feeling of sleep sufficiency, and positively with sleep length on weekdays relative to workdays, sleeping later than one would like, and a feeling of fatigue. Several relationships between self-reported sleep outcomes and demographic variables were also identified.

Short Sleep Duration and Insomnia Symptoms were Associated with Lower Happiness Levels in Chinese Adults in Hong Kong

Study objective: To examine the association of sleep duration and insomnia symptoms with happiness. Methods: A random sample of 1691 Chinese adult (mean age 54 ± 20.1, male 51%) were interviewed in a population-based telephone survey. Happiness was measured by the subjective happiness scale (SHS) and the one-item global happiness index (GHI). Information on sleep included mean past seven-day sleep duration (<6 h, ≥6 to <8 h and ≥8 h) and insomnia symptoms: Difficulty in initiating sleep (DIS), difficulty in maintaining sleep (DMS), and early morning awakening (EMA). Adjusted beta-coefficient (β) of SHS and adjusted odds ratio (aOR) of GHI in relation to sleep problems were calculated. Interaction effects by age (18–65 vs. ≥65) and by sex were assessed. Results: Compared to ≥8 h of sleep, having <6 h of sleep had lower SHS (adjusted β −0.32, 95% CI −0.46 to −0.17) and GHI (aOR 0.54, 95% CI 0.38 to 0.78). The associations were stronger in younger adults and in women (p < 0.05). DIS, DMS, and EMA were associated with lower SHS (adjusted β ranged from −0.20 to −0.06) and GHI (aOR ranged from 0.57 to 0.89). Dose-response association between the number of insomnia symptoms and lower SHS was observed (p < 0.001). These associations were generally stronger in older adults and among women. Conclusions: Lower levels of happiness were observed, particularly in younger adults and females with short sleep duration and older adults and females with insomnia symptoms. Prospective studies are needed to confirm the findings and understand the mechanisms between sleep and happiness.

An Integrated Model of Slow-Wave Activity and Neuroplasticity Impairments in Major Depressive Disorder

PURPOSE OF REVIEW

In this review, we aim to integrate the most recent research highlighting alterations in sleep slow-wave activity (SWA), and impairments in neuroplasticity in major depressive disorder (MDD) into a novel model of disorder maintenance.

RECENT FINDINGS

Sleep homeostasis has been shown to be impaired in MDD, with a subset of individuals also demonstrating impaired SWA. SWA is considered a marker of the homeostatic regulation of sleep, and is implicated in the downscaling of synaptic strength in the context of maintaining homeostatic plasticity. Individuals with MDD have been shown to exhibit impairments in both neural plasticity such as loss of dendritic branching, and synaptic plasticity such as decreased long-term potentiation-dependent learning and memory. Alterations in the homeostatic regulation of sleep, SWA, and synaptic plasticity in MDD suggest an underlying impairment in the modulation of synaptic strength. One candidate mechanism for this impairment is AMPA receptor trafficking.

Neurobiological mechanisms underlying the sleep-pain relationship in adolescence: A review

Adolescence characterizes a period of significant change in brain structure and function, causing the neural circuitry to be particularly susceptible to the environment and various other experiences. Chronic pain and sleep deprivation represent major health issues that plague adolescence. A bidirectional relationship exists between sleep and pain; however, emerging evidence suggests that sleep disturbances have a stronger influence on subsequent pain than vice versa. The neurobiological underpinnings of this relationship, particularly during adolescence, are poorly understood. This review examines the current literature regarding sleep and pain in adolescence, with a particular focus on the neurobiological mechanisms underlying pain, sleep problems, and the neural circuitry that potentially links the two. Finally, a research agenda is outlined to stimulate future research on this topic. Given the high prevalence of these health issues during adolescence and the debilitating effects they inflict on nearly every domain of development, it is crucial that we determine the neurobiological mechanisms fundamental to this relationship and identify potential therapeutic strategies.

Sex differences in sleep and sleep loss-induced cognitive deficits: The influence of gonadal hormones

Males and females can respond differentially to the same environmental stimuli and experimental conditions. Chronic sleep loss is a frequent and growing problem in many modern societies and has a broad variety of negative outcomes for health and well-being. While much has been done to explore the deleterious effects of sleep deprivation (SD) on cognition in both human and animal studies over the last few decades, very little attention has been paid to the part played by sex differences and gonadal steroids in respect of changes in cognitive functions caused by sleep loss. The effects of gonadal hormones on sleep regulation and cognitive performances are well established. Reduced gonadal function in menopausal women and elderly men is associated with sleep disturbances and cognitive decline as well as dementia, which suggests that sex steroids play a key role in modulating these conditions. Finding out whether there are sex differences in respect of the effect of insufficient sleep on cognition, and how neuroendocrine mediators influence cognitive impairment induced by SD could provide valuable insights into the best therapies for each sex. In this review, we aim to highlight the involvement of sex differences and gonadal hormone status on the severity of cognitive deficits induced by sleep deficiency in both human and animal studies.

Gender effects on auditory P300: A systematic review

The evidence suggests that gender-related effects could influence the electrophysiological P300 parameters and stand as an additional source of variation for both clinical and non-clinical subjects. The aim of this paper is to characterize gender-related differences in P300 potential as elicited with simple auditory paradigms. This knowledge (1) is important for the practical assessment of P300 potential in normal and clinical populations, and (2) can provide an insight into the understanding of gender differences in pathophysiology, particularly those with differential risk or prevalence in males and females. With this review it is shown that a limited number of studies encounter possible gender effects on parameters of auditory P300, and the findings need to be read with caution due to methodological limitations of the studies. Nevertheless, evidence supports that the P300 amplitude could be significantly modulated by gender, with greater amplitude in females relative to males. Noteworthy, gender has a minimal effect on the P300 latency, and it is often comparable between males and females. Furthermore, the effect of gender on P300 could be modulated by hormonal background, anatomy and some methodological aspects.

Cross-species systems analysis identifies gene networks differentially altered by sleep loss and depression

To understand the transcriptomic organization underlying sleep and affective function, we studied a population of (C57BL/6J × 129S1/SvImJ) F2 mice by measuring 283 affective and sleep phenotypes and profiling gene expression across four brain regions. We identified converging molecular bases for sleep and affective phenotypes at both the single-gene and gene-network levels. Using publicly available transcriptomic datasets collected from sleep-deprived mice and patients with major depressive disorder (MDD), we identified three cortical gene networks altered by the sleep/wake state and depression. The network-level actions of sleep loss and depression were opposite to each other, providing a mechanistic basis for the sleep disruptions commonly observed in depression, as well as the reported acute antidepressant effects of sleep deprivation. We highlight one particular network composed of circadian rhythm regulators and neuronal activity-dependent immediate-early genes. The key upstream driver of this network, Arc, may act as a nexus linking sleep and depression. Our data provide mechanistic insights into the role of sleep in affective function and MDD.

Relationships Amongst Aggression, Self-Theory, Loneliness, and Depression in Emerging Adults

The purpose of this study was to examine the relationships amongst aggression, self-theory, loneliness, and depression. The study group consisted of 904 student volunteers from various undergraduate programs of a university in Central Anatolia. Simple and hierarchical multiple linear regression analyses, as well as t-tests, were used to analyze the data. In the preliminary analysis performed, females’ depression levels and males’ aggression levels are higher. The study findings revealed that self-theory negatively and significantly predicted aggression, whereas loneliness and depression positively and significantly predicted aggression in emerging adulthood. Another important finding showed that both direct and indirect relationships exist between self-theory and aggression. According to these findings, loneliness and depression play partially mediating roles individually, and fully mediating roles together, with regard to the relationship between self-theory and aggression.

Regular Practice of Competitive Sports Does Not Impair Sleep in Adolescents: DADOS Study

PURPOSE

To analyze differences in sleep quality and duration by athletic status and sex, and to examine the association between physical activity (PA) recommendation and sleep in adolescents.

METHODS

A total of 267 adolescents [13.9 (0.3) y] from Deporte, ADOlescencia y Salud (DADOS) study (129 girls) were included in this cross-sectional analysis. Athletes competed regularly in organized sport events and trained ≥3 days per week, but nonathletes did not compete. PA was assessed by GENEActiv accelerometer. PA values were dichotomized into inactive (<60 min/d of moderate and vigorous PA) and active (≥60 min/d of moderate and vigorous PA). Sleep quality was evaluated with the Spanish version of the Pittsburgh Sleep Quality Index. Pittsburgh Sleep Quality Index values were dichotomized into >5 (poor quality) or ≤5 (good quality). Sleep duration was objectively measured by accelerometer.

RESULTS

Sleep quality and duration were not statistically different between athletes [median (Mdn) = 4.0, interquartile range (IQR) = 3.0-6.0 and Mdn = 8.0, IQR = 7.4-8.6 h, respectively] and nonathletes (Mdn = 5.0, IQR = 3.0-7.0 and Mdn = 7.9; IQR = 7.3-8.6 h, respectively), P > .05. Nonathlete or inactive adolescents did not show higher risk for poor sleep quality or short sleep duration than athletes [odds ratio (OR) = 1.17; 95% confidence interval (CI), 0.68-2.00 and OR = 0.93; 95% CI, 0.56-1.55, respectively] or active peers (OR = 1.39; 95% CI, 0.66-2.89 and OR = 1.62; 95% CI, 0.78-3.37, respectively).

CONCLUSIONS

In our group of adolescents, competitive sport practice did not alter sleep patterns. PA recommendations for adolescents may not discriminate between good and poor sleepers.

Impact of sex steroids and reproductive stage on sleep-dependent memory consolidation in women

Age and sex are two of the three major risk factors for Alzheimer's disease (ApoE-e4 allele is the third), with women having a twofold greater risk for Alzheimer's disease after the age of 75 years. Sex differences have been shown across a wide range of cognitive skills in young and older adults, and evidence supports a role for sex steroids, especially estradiol, in protecting against the development of cognitive decline in women. Sleep may also be a protective factor against age-related cognitive decline, since specific electrophysiological sleep events (e.g. sleep spindle/slow oscillation coupling) are critical for offline memory consolidation. Furthermore, studies in young women have shown fluctuations in sleep events and sleep-dependent memory consolidation during different phases of the menstrual cycle that are associated with the levels of sex steroids. An under-appreciated possibility is that there may be an important interaction between these two protective factors (sex steroids and sleep) that may play a role in daily fluctuations in cognitive processing, in particular memory, across a woman's lifespan. Here, we summarize the current knowledge of sex steroid-dependent influences on sleep and cognition across the lifespan in women, with special emphasis on sleep-dependent memory processing. We further indicate gaps in knowledge that require further experimental examination in order to fully appreciate the complex and changing landscape of sex steroids and cognition. Lastly, we propose a series of testable predictions for how sex steroids impact sleep events and sleep-dependent cognition across the three major reproductive stages in women (reproductive years, menopause transition, and post-menopause).

Determinants of Slow-Wave Activity in Overweight and Obese Adults: Roles of Sex, Obstructive Sleep Apnea and Testosterone Levels

Background: Slow-wave activity (SWA) in non-rapid eye movement (NREM) sleep, obtained by spectral analysis of the electroencephalogram, is a marker of the depth or intensity of NREM sleep. Higher levels of SWA are associated with lower arousability during NREM sleep and protect against sleep fragmentation. Multiple studies have documented that SWA levels are higher in lean women, compared to age-matched lean men, but whether these differences persist in obese subjects is unclear. Obstructive sleep apnea (OSA), a condition associated with obesity, is more prevalent in men than in women. Sex differences in SWA could therefore be one of the factors predisposing men to OSA. Furthermore, we hypothesized that higher levels of testosterone may be associated with lower levels of SWA. Objective: The aim of the current study was to identify sex differences in the determinants of SWA in young and middle-aged overweight and obese adults. Methods: We enrolled 101 overweight and obese but otherwise healthy participants from the community (44 men, 57 women) in this cross-sectional study. Participants underwent an overnight in-laboratory polysomnogram. The recordings were submitted to sleep staging and spectral analysis. Sex differences and the potential contribution of testosterone levels were evaluated after adjusting for age, body mass index and race/ethnicity. Results: OSA was present in 66% of men and in 44% of women. After adjustment for differences in age, race/ethnicity and BMI, the odds ratio for OSA in men vs. women was 3.17 (95% CI 1.14-9.43, p = 0.027). There was a graded inverse relationship between the apnea-hypopnea index (AHI) and SWA in men (β = -0.21, p = 0.018) but not in women (β = 0.10, p = 0.207). In a multivariate regression model, higher testosterone levels were independently associated with lower SWA in men after controlling for age, race/ethnicity and apnea-hypopnea index (β = -0.56, p = 0.025). Conclusion: Increasing severity of OSA was associated with significant decrease in sleep intensity in men but not in women. Higher testosterone levels were associated with lower sleep intensity in men. Men with higher testosterone levels may therefore have lower arousal thresholds and higher ventilatory instability in NREM sleep, and be at greater risk of OSA.

Stress and Sleep: Results from the Hispanic Community Health Study/Study of Latinos Sociocultural Ancillary Study

Hispanics/Latinos face specific sociocultural stressors associated with their marginalized status in the United States. While stress is known to cause poor sleep, the differential effects of the specific stressors faced by Hispanics/Latinos have not been evaluated. Using cross-sectional data from the Hispanic Community Health Study/Study of Latinos Sociocultural Ancillary Study, we conducted weighted generalized linear models to evaluate the associations of acculturation stress, ethnic discrimination, and chronic moderate/severe stress with self-reported sleep outcomes (insomnia symptoms, daytime sleepiness, sleep duration) in individual and aggregate models adjusted for site, socio-demographics, behavioral, and medical conditions. Participants included 5313 Hispanic/Latino adults; 43.5% ≥ age 45, 54.8% female, and 22.0% US-born. Chronic moderate/severe stress, ethnic discrimination, and acculturation stress were each positively associated with sleep. In the adjusted aggregate model, only chronic moderate/severe stress was associated with insomnia symptoms (exp(b) = 1.07 for each additional stressor, 95% CI = 1.05, 1.09). Both acculturation stress (exp(b) = 1.05 for each additional SD, 95% CI = 1.02, 1.10) and ethnic discrimination (exp(b) = 1.05 for each additional SD, 95% CI = 1.01, 1.08) were associated with daytime sleepiness. Each SD increase in ethnic discrimination related to a 16% and 13% increased prevalence of short (< 7 h) (RRR = 1.16, 95% CI = 1.02, 1.31) and long sleep duration (> 9 h) (RRR = 1.13, 95% CI = 1.00, 1.27), respectively. These associations were consistent across sex. Acculturation stress and ethnic discrimination are associated with poor sleep in Hispanics/Latinos. Future research should explore whether behavioral sleep interventions minimize the impact of sociocultural stressors on sleep.

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Latina/os face unique stressors associated with their marginalized status in the USA.

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We explored the association of sociocultural stressors with Latina/o sleep.

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Acculturation stress and ethnic discrimination were associated with daytime sleepiness.

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Only chronic psychosocial stress was associated with insomnia symptoms.

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Ethnic discrimination was associated with both short and long sleep duration.

Changes in Brain-Derived Neurotrophic Factor Expression Influence Sleep-Wake Activity and Homeostatic Regulation of Rapid Eye Movement Sleep

Study Objectives

Brain-derived neurotrophic factor (BDNF) expression and homeostatic regulation of rapid eye movement (REM) sleep are critical for neurogenesis and behavioral plasticity. Accumulating clinical and experimental evidence suggests that decreased BDNF expression is causally linked with the development of REM sleep-associated neuropsychiatric disorders. Therefore, we hypothesize that BDNF plays a role in sleep–wake (S–W) activity and homeostatic regulation of REM sleep.

Methods

Male and female wild-type (WT; BDNF +/+) and heterozygous BDNF (KD; BDNF +/−) rats were chronically implanted with S–W recording electrodes to quantify baseline S–W activity and REM sleep homeostatic regulatory processes during the light phase.

Results

Molecular analyses revealed that KD BDNF rats had a 50% decrease in BDNF protein levels. During baseline S–W activity, KD rats exhibited fewer REM sleep episodes that were shorter in duration and took longer to initiate. Also, the baseline S–W activity did not reveal any sex difference. During the 3-hour selective REM sleep deprivation, KD rats failed to exhibit a homeostatic drive for REM sleep and did not exhibit rebound REM sleep during the recovery S–W period.

Conclusion

Interestingly, both genotypes did not reveal any sex difference in the quality and/or quantity of REM sleep. Collectively, these results, for the first time, unequivocally demonstrate that an intact BDNF system in both sexes is a critical modulator for baseline and homeostatic regulation of REM sleep. This study further suggests that heterozygous BDNF knockdown rats are a useful animal model for the study of the cellular and molecular mechanisms of sleep regulation and cognitive functions of sleep.

Ovarian hormones, sleep and cognition across the adult female lifespan: An integrated perspective

Loss of ovarian function in women is associated with sleep disturbances and cognitive decline, which suggest a key role for estrogens and/or progestins in modulating these symptoms. The effects of ovarian hormones on sleep and cognitive processes have been studied in separate research fields that seldom intersect. However, sleep has a considerable impact on cognitive function. Given the tight connections between sleep and cognition, ovarian hormones may influence selective aspects of cognition indirectly, via the modulation of sleep. In support of this hypothesis, a growing body of evidence indicates that the development of sleep disorders following menopause contributes to accelerated cognitive decline and dementia in older women. This paper draws from both the animal and human literature to present an integrated view of the effects of ovarian hormones on sleep and cognition across the adult female lifespan.

Neurophysiological correlates of suicidal ideation in major depressive disorder: Hyperarousal during sleep

BACKGROUND

Suicide is a major public health concern, and a barrier to reducing the suicide rate is the lack of objective predictors of risk. The present study considers whether quantitative sleep electroencephalography (EEG) may be a neurobiological correlate of suicidal ideation.

METHODS

Participants included 84 (45 female, mean age=26.6) adults diagnosed with major depressive disorder (MDD). The item that measures thoughts of death or suicide on the Quick Inventory of Depressive Symptomatology (QIDS) was used to classify 47 participants as low suicidal ideation (24 females, mean age=26.1) and 37 as high suicidal ideation (21 females, mean age=27.3). Data were obtained from archival samples collected at the University of Michigan and University of Texas Southwestern Medical Center between 2004 and 2012. Sleep EEG was quantified using power spectral analysis, and focused on alpha, beta, and delta frequencies.

RESULTS

Results indicated that participants with high compared to low suicidal ideation experienced 1) increased fast frequency activity, 2) decreased delta activity, and 3) increased alpha-delta sleep after adjusting for age, sex, depression, and insomnia symptoms.

LIMITATIONS

Limitations include the exclusion of imminent suicidal intent, a single suicidal ideation item, and cross-sectional archival data.

CONCLUSIONS

This is one of the first studies to provide preliminary support that electrophysiological brain activity during sleep is associated with increased suicidal ideation in MDD, and may point toward central nervous system (CNS) hyperarousal during sleep as a neurobiological correlate of suicidal ideation.

Poor Sleep Is Related to Lower Emotional Competence Among Adolescents

The aim of the present study was to explore the association between subjective insomnia and self-reported emotional competence in areas such as regulating and perceiving one's own emotions and empathy, in a sample of adolescents. Gender differences were also explored. 366 adolescents in 10th to 12th grade (mean age: M = 16.9 years) took part in this cross-sectional study. They completed questionnaires related to emotional competencies, empathy, and sleep. Higher scores for insomnia were associated with lower scores for some aspects of emotional competence and empathy. Compared to males, females generally had higher scores for emotional competence. Poor sleep as subjectively experienced among adolescents is associated with specific impairments in emotional competence and empathy. Gender-related patterns were also observed.

Sleep Architecture Relates to Daytime Affect and Somatic Complaints in Clinically Anxious but Not Healthy Children

It is increasingly clear that seminal sleep-affective relationships begin to take root in childhood, yet studies exploring how nighttime sleep characteristics relate to daytime affective symptoms, both in clinical and healthy populations of children, are lacking. The current study sought to explore these relationships by investigating whether trait-like and/or daily reports of affective and somatic symptoms of children with generalized anxiety disorder and matched controls relate to sleep architecture. Sixty-six children (ages 7-11; 54.4% female; 56.1% Caucasian; 18.2% biracial; 6.1% African American; 3% Asian; 16.7% Hispanic) participated including 29 with primary generalized anxiety disorder (without comorbid depression) and 37 healthy controls matched on age and race/ethnicity. Participants underwent structured diagnostic assessments including child-report measures and subsequently reported on their negative affect and somatic symptoms over the course of 1 week. Children also completed 1 night of polysomnography. Among children with generalized anxiety disorder only, greater amounts of slow wave sleep corresponded with less negative affect, and greater amounts of rapid eye movement sleep was related to more somatic complaints across the week. Similarly, for trait-like measures, more rapid eye movement sleep and shorter latency to rapid eye movement sleep were related to greater depressive symptoms in the anxious group only. The current findings suggest that physiologic sleep characteristics may contribute in direct ways to the symptom profiles of clinically anxious children. The functional relevance of such findings (e.g., how specific sleep characteristics serve to either increase or reduce long-term risk) is a vital direction for future research.

The Origins of Mental Toughness - Prosocial Behavior and Low Internalizing and Externalizing Problems at Age 5 Predict Higher Mental Toughness Scores at Age 14

Background: The concept of mental toughness (MT) has gained increasing importance among groups other than elite athletes by virtue of its psychological importance and explanatory power for a broad range of health-related behaviors. However, no study has focused so far on the psychological origins of MT. Therefore, the aims of the present study were: to explore, to what extent the psychological profiles of preschoolers aged five were associated with both (1) MT scores and (2) sleep disturbances at age 14, and 3) to explore possible gender differences.

Method: Nine years after their first assessment at age five (preschoolers), a total of 77 adolescents (mean age: 14.35 years; SD = 1.22; 42% females) took part in this follow-up study. At baseline, both parents and teachers completed the Strengths and Difficulties Questionnaire (SDQ), covering internalizing and externalizing problems, hyperactivity, negative peer relationships, and prosocial behavior. At follow-up, participants completed a booklet of questionnaires covering socio-demographic data, MT, and sleep disturbances.

Results: Higher prosocial behavior, lower negative peer relationships, and lower internalizing and externalizing problems at age five, as rated by parents and teachers, were associated with self-reported higher MT and lower sleep disturbances at age 14. At age 14, and relative to males, females had lower MT scores and reported more sleep disturbances.

Conclusion: The pattern of results suggests that MT traits during adolescence may have their origins in the pre-school years.

Age-Related Differences in Sleep Architecture and Electroencephalogram in Adolescents in the National Consortium on Alcohol and Neurodevelopment in Adolescence Sample

STUDY OBJECTIVES

To investigate age-related differences in polysomnographic and sleep electroencephalographic (EEG) measures, considering sex, pubertal stage, ethnicity, and scalp topography in a large group of adolescents in the National Consortium on Alcohol and NeuroDevelopment in Adolescence (NCANDA).

METHODS

Following an adaptation/clinical screening night, 141 healthy adolescents (12-21 y, 64 girls) had polysomnographic recordings, from which sleep staging and EEG measures were derived. The setting was the SRI International Human Sleep Laboratory and University of Pittsburgh Pediatric Sleep Laboratory.

RESULTS

Older age was associated with a lower percentage of N3 sleep, accompanied by higher percentages of N2, N1, and rapid eye movement (REM) sleep. Older boys compared with younger boys had more frequent awakenings and wakefulness after sleep onset, effects that were absent in girls. Delta (0.3-4 Hz) EEG power in nonrapid eye movement NREM sleep was lower in older than younger adolescents at all electrode sites, with steeper slopes of decline over the occipital scalp. EEG power in higher frequency bands was also lower in older adolescents than younger adolescents, with equal effects across electrodes. Percent delta power in the first NREM period was similar across age. African Americans had lower EEG power across frequency bands (delta to sigma) compared with Caucasians. Finally, replacing age with pubertal status in the models showed similar relationships.

CONCLUSIONS

Substantial differences in sleep architecture and EEG were evident across adolescence in this large group, with sex modifying some relationships. Establishment and follow-up of this cohort allows the investigation of sleep EEG-brain structural relationships and the effect of behaviors, such as alcohol and substance use, on sleep EEG maturation.

24-h activity rhythm and sleep in depressed outpatients

Disturbances in sleep and circadian rest-activity rhythms are key features of depression. Actigraphy, a non-invasive method for monitoring motor activity, can be used to objectively assess circadian rest-activity rhythms and sleep patterns. While recent studies have measured sleep and daytime activity of depressed patients using wrist-worn actigraphy, the actigraphic 24-h rest-activity rhythm in depression has not been well documented. We aimed to examine actigraphically measured sleep and circadian rest-activity rhythms in depressed outpatients. Twenty patients with DSM-IV major depressive episode and 20 age- and sex-matched healthy controls participated in this study. Participants completed 7 consecutive days of all-day actigraphic activity monitoring while engaging in usual activities. For sleep parameters, total sleep time, wake after sleep onset, and sleep fragmentation index were determined. Circadian rhythms were estimated by fitting individual actigraphy data to a cosine curve of a 24-h activity rhythm using the cosinor method, which generated three circadian activity rhythm parameters, i.e., MESOR (rhythm-adjusted mean), amplitude, and acrophase. Subjective sleep was also assessed using a sleep diary and the Pittsburgh Sleep Quality Index. Patients showed significantly lower MESOR and more dampened amplitude along with significant sleep disturbances. Logistic regression analysis revealed that lower MESOR and more fragmented sleep emerged as the significant predictors of depression. Correlations between subjectively and actigraphically measured parameters demonstrated the validity of actigraphic measurements. These results indicate marked disturbances in sleep and circadian rest-activity rhythms of depression. By simultaneously measuring sleep and rest-activity rhythm parameters, actigraphy might serve as an objective diagnostic aid for depression.

During early to mid adolescence, moderate to vigorous physical activity is associated with restoring sleep, psychological functioning, mental toughness and male gender

Numerous studies showed that regular physical activity (PA) is associated with both favourable and restorative sleep and improved psychological functioning (PF). However, there is little research on the topic covering the early to mid-adolescence period. Moreover, curiosity and exploratory behaviour (CEB) and mental toughness (MT) as a result of PA remains thus far uninvestigated, as do possible gender differences. The aim of the present study was to explore the associations between PA, subjective sleep (sS), PF, CEB, and MT during early to mid-adolescence. A total of 1361 participants (mean age = 13.37 years; range: 11-16 years; 51.2% female) took part in the study. They completed questionnaires covering PA, sS, PF, CEB, and MT. Greater PA was related to improved PF, better sS, and increased CEB and MT. Compared to male participants, females reported less PA, poorer sS, and had lower PF and MT scores. The present pattern of results suggests that during early and mid-adolescence greater PA was associated with more favourable sS and better PF, including CEB and MT, and that female participants reported lower scores in PA, sS, and PF. Accordingly, if PA has a favourable impact on sleep and psychological functioning, then data suggest that sports participation should be more tailored to increase motivation among female adolescents.

Sex differences in sleep: impact of biological sex and sex steroids

Men and women sleep differently. While much is known about the mechanisms that drive sleep, the reason for these sex differences in sleep behaviour is unknown and understudied. Historically, women and female animals are underrepresented in studies of sleep and its disorders. Nevertheless, there is a growing recognition of sex disparities in sleep and rhythm disorders. Women typically report poorer quality and more disrupted sleep across various stages of life. Findings from clinical and basic research studies strongly implicate a role for sex steroids in sleep modulation. Understanding how neuroendocrine mediators and sex differences influence sleep is central to advancing our understanding of sleep-related disorders. The investigation into sex differences and sex steroid modulation of sleep is in its infancy. Identifying the mechanisms underlying sex and gender differences in sleep will provide valuable insights leading to tailored therapeutics that benefit each sex. The goal of this review is to discuss our current understanding of how biological sex and sex steroids influence sleep behaviour from both the clinical and pre-clinical perspective.

Sex-specific sleep patterns among university students in Lebanon: impact on depression and academic performance

Good sleep quality and quantity are fundamental to the maintenance of normal physiological processes. Changes in sleep patterns are commonly observed among young adults and are shown to impact neurocognitive, academic, and psychological well-being. Given the scarcity of sleep information about Lebanon and acknowledging the sex differences in various sleep dimensions, we conducted a study that aimed at assessing sex differences in sleep habits among university students in Lebanon in relation to psychoacademic status. A total of 540 students (50.6% females) completed a questionnaire that inquired about sociodemographics and evaluated sleep quality and depression using the Pittsburg Sleep Quality Index (PSQI) and Center for Epidemiological Studies Depression Scale (CES-D), respectively. The mean PSQI global score (6.57±3.49) indicated poor sleep, with no significant differences between men and women. The sleep/wake rhythm was delayed on weekends for both sexes. Females exhibited earlier bedtimes and rise times and longer sleep durations on both weekdays and weekends. However, unlike males females showed a greater phase delay in wake times than bedtimes on weekends (149 minutes vs 74 minutes, respectively). In all, 70.9% of females suffered from depressive symptoms, which was a significantly higher proportion compared with 58.5% of males (P<0.01). Based on the mean cumulative self-reported grade point average (GPA), the academic performance of females was significantly better than that of males (2.8±0.61 vs 2.65±0.61, P<0.05, respectively). Depression, as scored by CES-D, in females was significantly negatively correlated with the cumulative GPA (r=-0.278, P<0.01), earlier wake time (r=-0.168, P<0.05), and average sleep duration (r=-0.221, P<0.01) on weekdays. GPA of males was significantly correlated with bedtime on weekends (r=-0.159, P<0.05). We conclude that sex differences in sleep timing, such as bedtime/rise time and nocturnal sleep duration, rather than sleep quality exist among Lebanese university students. Sex-specific sleep patterns have differential impact on psychological and academic well-being.

The Neurobiology of Sleep and Wakefulness

Cortical electroencephalographic activity arises from corticothalamocortical interactions, modulated by wake-promoting monoaminergic and cholinergic input. These wake-promoting systems are regulated by hypothalamic hypocretin/orexins, while GABAergic sleep-promoting nuclei are found in the preoptic area, brainstem and lateral hypothalamus. Although pontine acetylcholine is critical for REM sleep, hypothalamic melanin-concentrating hormone/GABAergic cells may "gate" REM sleep. Daily sleep-wake rhythms arise from interactions between a hypothalamic circadian pacemaker and a sleep homeostat whose anatomical locus has yet to be conclusively defined. Control of sleep and wakefulness involves multiple systems, each of which presents vulnerability to sleep/wake dysfunction that may predispose to physical and/or neuropsychiatric disorders.

The role of fast and slow EEG activity during sleep in males and females with major depressive disorder

Sleep difficulties are highly prevalent in depression, and appear to be a contributing factor in the development and maintenance of symptoms. However, despite the generally acknowledged relationship between sleep and depression, the neurophysiological substrates underlying this relationship still remain unclear. Two main hypotheses were tested in this study. The first hypothesis states that sleep in depression is characterized by inadequate generation of restorative sleep, as indexed by reduced amounts of slow-wave activity. Conversely, the second hypothesis states that poor sleep in depression is due to intrusions of fast-frequency activity that may be reflective of a hyperaroused central nervous system. This study aimed to test both hypotheses in a large sample of individuals with clinically validated depression, as well as to examine sex as a moderator. Results suggest that depression is better characterized by an overall decrease in slow-wave activity, which is related to elevated anxious and depressed mood the following morning. Results also suggest that females may be more likely to experience fast frequency activity related to depression symptom severity.

Reduction in delta activity predicted improved negative affect in Major Depressive Disorder

While prior research has demonstrated a paradoxical antidepressant effect of slow-wave disruption (SWD), the specific dimensions of depression affected is still unclear. The current study aimed to extend this research by utilizing a dimensional approach in examining the antidepressant effects of SWD. Of particular interest is the affective dimension, as negative affect in depression is arguably the most salient characteristic of depression. This sample included 16 individuals with depression (10 female) recruited from the community. Participants slept in the lab for three nights (adaptation, baseline night, and SWD) with polysomnography, and completed measures of negative affect and depression severity the following morning. Results show that reduction in delta power was linearly associated with improved negative affect. Comparison of individual change scores revealed that half of the individuals showed improved negative affect, which is comparable to the reported 40-60% antidepressant response rate to sleep deprivation. Results suggest that vulnerability in the sleep homeostatic system may be a contributing individual differences factor in response to slow-wave disruption in depression.