Adolescent sleep patterns in humans and laboratory animals

Adolescents' trajectories of depression and anxiety symptoms prior to and during the COVID-19 pandemic and their association with healthy sleep patterns

The COVID-19 pandemic has seen a rise in anxiety and depression among adolescents. This study aimed to investigate the longitudinal associations between sleep and mental health among a large sample of Australian adolescents and examine whether healthy sleep patterns were protective of mental health in the context of the COVID-19 pandemic. We used three waves of longitudinal control group data from the Health4Life cluster-randomized trial (N = 2781, baseline Mage = 12.6, SD =  0.51; 47% boys and 1.4% 'prefer not to say'). Latent class growth analyses across the 2 years period identified four trajectories of depressive symptoms: low-stable (64.3%), average-increasing (19.2%), high-decreasing (7.1%), moderate-increasing (9.4%), and three anxiety symptom trajectories: low-stable (74.8%), average-increasing (11.6%), high-decreasing (13.6%). We compared the trajectories on sociodemographic and sleep characteristics. Adolescents in low-risk trajectories were more likely to be boys and to report shorter sleep latency and wake after sleep onset, longer sleep duration, less sleepiness, and earlier chronotype. Where mental health improved or worsened, sleep patterns changed in the same direction. The subgroups analyses uncovered two important findings: (1) the majority of adolescents in the sample maintained good mental health and sleep habits (low-stable trajectories), (2) adolescents with worsening mental health also reported worsening sleep patterns and vice versa in the improving mental health trajectories. These distinct patterns of sleep and mental health would not be seen using mean-centred statistical approaches.

Circadian neurogenetics and its implications in neurophysiology, behavior, and chronomedicine

The circadian rhythm affects multiple physiological processes, and disruption of the circadian system can be involved in a range of disease-related pathways. The genetic underpinnings of the circadian rhythm have been well-studied in model organisms. Significant progress has been made in understanding how clock genes affect the physiological functions of the nervous system. In addition, circadian timing is becoming a key factor in improving drug efficacy and reducing drug toxicity. The circadian biology of the target cell determines how the organ responds to the drug at a specific time of day, thus regulating pharmacodynamics. The current review brings together recent advances that have begun to unravel the molecular mechanisms of how the circadian clock affects neurophysiological and behavioral processes associated with human brain diseases. We start with a brief description of how the ubiquitous circadian rhythms are regulated at the genetic, cellular, and neural circuit levels, based on knowledge derived from extensive research on model organisms. We then summarize the latest findings from genetic studies of human brain disorders, focusing on the role of human clock gene variants in these diseases. Lastly, we discuss the impact of common dietary factors and medications on human circadian rhythms and advocate for a broader application of the concept of chronomedicine.

Feasibility of applying a noninvasive method for sleep monitoring based on mouse behaviors

INTRODUCTION

Currently, electroencephalogram (EEG)/electromyogram (EMG) system is widely regarded as the "golden standard" for sleep monitoring. Imperfectly, its invasive monitoring may somehow interfere with the natural state of sleep. Up to now, noninvasive methods for sleep monitoring have developed, which could preserve the undisturbed and naïve sleep state of mice to the greatest extent, but the feasibility of their application under different conditions should be extensive validated.

METHODS

Based on existing research, we verified the feasibility of a sleep monitoring system based on mouse behaviors under different conditions. The experimental mice were exposed to various stresses and placed into a combined device comprising noninvasive sleep monitoring equipment and an EEG/EMG system, and the sleep status was recorded under different physiological, pharmacological, and pathophysiological conditions. The consistency of the parameters obtained from the different systems was calculated using the Bland-Altman statistical method.

RESULTS

The results demonstrated that the physiological sleep times determined by noninvasive sleep monitoring system were highly consistent with those obtained from the EEG/EMG system, and the coefficients were 94.4% and 95.1% in C57BL/6J and CD-1 mice, respectively. The noninvasive sleep monitoring system exhibited high sensitivity under the sleep-promoting effect of diazepam and caffeine-induced wakefulness, which was indicated by its ability to detect the effect of dosage on sleep times, and accurate determination of the sleep/wakeful status of mice under different pathophysiological conditions. After combining the data obtained from all the mice, the coefficient between the sleep times detected by behavior-based sleep monitoring system and those obtained from the EEG/EMG equipment was determined to .94.

CONCLUSION

The results suggested that behavior-based sleep monitoring system could accurately evaluate the sleep/wakeful states of mice under different conditions.

In vivo marker of brainstem myelin is associated to quantitative sleep parameters in healthy young men

The regional integrity of brain subcortical structures has been implicated in sleep-wake regulation, however, their associations with sleep parameters remain largely unexplored. Here, we assessed association between quantitative Magnetic Resonance Imaging (qMRI)-derived marker of the myelin content of the brainstem and the variability in the sleep electrophysiology in a large sample of 18-to-31 years healthy young men (N = 321; ~ 22 years). Separate Generalized Additive Model for Location, Scale and Shape (GAMLSS) revealed that sleep onset latency and slow wave energy were significantly associated with MTsat estimates in the brainstem (pcorrected ≤ 0.03), with overall higher MTsat value associated with values reflecting better sleep quality. The association changed with age, however (MTsat-by-age interaction-pcorrected ≤ 0.03), with higher MTsat value linked to better values in the two sleep metrics in the younger individuals of our sample aged ~ 18 to 20 years. Similar associations were detected across different parts of the brainstem (pcorrected ≤ 0.03), suggesting that the overall maturation and integrity of the brainstem was associated with both sleep metrics. Our results suggest that myelination of the brainstem nuclei essential to regulation of sleep is associated with inter-individual differences in sleep characteristics during early adulthood. They may have implications for sleep disorders or neurological diseases related to myelin.

How do adolescents experience a newly developed Online Single Session Sleep Intervention? A Think-Aloud Study

BACKGROUND

Sleep problems are common in adolescents and have detrimental impacts on physical and mental health and daily functioning. Evidence-based treatment like cognitive behaviour therapy for insomnia (CBT-I) is often hard to access, and adolescents may not engage in and adhere to longer, clinician-delivered interventions. Brief, self-guided, and accessible sleep interventions are needed.

OBJECTIVE

To explore the user experience of a prototype online self-help single session sleep intervention developed for adolescents.

METHODS

Eleven participants aged 17-19 years (8 females, 3 males) took part in online retrospective think-aloud interviews. Participants first completed the prototype intervention independently and were then shown the intervention page by page and asked to verbalise their thoughts and experiences. Transcripts were analyzed thematically.

RESULTS

Participants found the intervention helpful. Four themes were generated - 'Educative: Learning, but more fun', 'Effortless: Quicker and Easier', 'Personalization: Power of Choice', and 'Positivity: Just Good Vibes'. The theme 'Educative: Learning, but more fun' encompassed two sub-themes 'Opportunity to Learn' and 'Aesthetics and Learning'. These themes reflected participants' views that the intervention was educative, personalised, solution-oriented and easy to use, but could incorporate more graphics and visuals to aid in learning and could be made more effortless and positive through modifications to its design.

CONCLUSIONS

Findings convey the importance of ensuring educative well-designed content, personalization, a positive tone, and ease of use while designing interventions targeting adolescents's sleep and mental health. They also indicate areas for further developing the intervention.

Pediatric sleep: current knowledge, gaps, and opportunities for the future

This White Paper addresses the current gaps in knowledge, as well as opportunities for future studies in pediatric sleep. The Sleep Research Society's Pipeline Development Committee assembled a panel of experts tasked to provide information to those interested in learning more about the field of pediatric sleep, including trainees. We cover the scope of pediatric sleep, including epidemiological studies and the development of sleep and circadian rhythms in early childhood and adolescence. Additionally, we discuss current knowledge of insufficient sleep and circadian disruption, addressing the neuropsychological impact (affective functioning) and cardiometabolic consequences. A significant portion of this White Paper explores pediatric sleep disorders (including circadian rhythm disorders, insomnia, restless leg and periodic limb movement disorder, narcolepsy, and sleep apnea), as well as sleep and neurodevelopment disorders (e.g. autism and attention deficit hyperactivity disorder). Finally, we end with a discussion on sleep and public health policy. Although we have made strides in our knowledge of pediatric sleep, it is imperative that we address the gaps to the best of our knowledge and the pitfalls of our methodologies. For example, more work needs to be done to assess pediatric sleep using objective methodologies (i.e. actigraphy and polysomnography), to explore sleep disparities, to improve accessibility to evidence-based treatments, and to identify potential risks and protective markers of disorders in children. Expanding trainee exposure to pediatric sleep and elucidating future directions for study will significantly improve the future of the field.

Continuous body temperature as a window into adolescent development

Continuous body temperature is a rich source of information on hormonal status, biological rhythms, and metabolism, all of which undergo stereotyped change across adolescence. Due to the direct actions of these dynamic systems on body temperature regulation, continuous temperature may be uniquely suited to monitoring adolescent development and the impacts of exogenous reproductive hormones or peptides (e.g., hormonal contraception, puberty blockers, gender affirming hormone treatment). This mini-review outlines how traditional methods for monitoring the timing and tempo of puberty may be augmented by markers derived from continuous body temperature. These features may provide greater temporal precision, scalability, and reduce reliance on self-report, particularly in females. Continuous body temperature data can now be gathered with ease across a variety of wearable form factors, providing the opportunity to develop tools that aid in individual, parental, clinical, and researcher awareness and education.

Learning to Learn: A pilot study on explicit strategy instruction to incoming college students

The current pilot study implemented a "Learning to Learn" (L2L) course designed to teach first-year college students about the science of how learning works, how to take ownership of their own learning, and how to effectively apply learning strategies to achieve their academic goals. A cognitive apprenticeship model was used in which students planned, executed, and evaluated strategy use in vivo during the course. Two sections of the course were taught at each of two different institutions, distributed across four semesters. Quantitative data showed an increased growth mindset among L2L students at the end of the semester compared to the beginning of the semester. In contrast, first-year students surveyed from control groups in the same semester had a decreased growth mindset. Furthermore, compared to students in the control groups, students in the L2L courses maintained more stable levels of effort across the semester and felt more in control of their learning by the end of the semester. Qualitative data collected from focus groups indicated that the L2L students continued to use the strategies they had learned in the course in the subsequent semester, and that the changes in their perceptions about growth mindset continued beyond the duration of the course. Several L2L students noted a desire for the learning strategies to be taught earlier in their education. Next steps involve feasibility studies on appropriate scaling to support more undergraduates each year, and to support students during the critical transition from K-12 schooling to the college environment.

Integration of Time-Based Recommendations with Current Pediatric Health Behavior Guidelines: Implications for Obesity Prevention and Treatment in Youth

PURPOSE OF REVIEW

Youth-onset obesity is associated with negative health outcomes across the lifespan including cardiovascular diseases, type 2 diabetes, obstructive sleep apnea, dyslipidemias, asthma, and several cancers. Pediatric health guidelines have traditionally focused on the quality and quantity of dietary intake, physical activity, and sleep.

RECENT FINDINGS

Emerging evidence suggests that the timing (time of day when behavior occurs) and composition (proportion of time spent allocated to behavior) of food intake, movement (i.e., physical activity, sedentary time), and sleep may independently predict health trajectories and disease risks. Several theoretically driven interventions and conceptual frameworks feature behavior timing and composition (e.g., 24 h movement continuum, circadian science and chronobiology, intermittent fasting regimens, structured day hypothesis). These literatures are, however, disparate, with little crosstalk across disciplines. In this review, we examine dietary, sleep, and movement guidelines and recommendations for youths ages 0-18 in the context of theoretical models and empirical findings in support of time-based approaches. The review aims to inform a unifying framework of health behaviors and guide future research on the integration of time-based recommendations into current quantity and quality-based health guidelines for children and adolescents.

Multidimensional self-rating biological rhythm disorder and its association with depression and anxiety symptoms among adolescents aged 11-23 years: a school-based cross-sectional study from China

BACKGROUND

Depression and anxiety are topical concerns worldwide, especially among adolescents. Besides, biological rhythm disorder as a candidate mechanism for mood disorders is highly prevalent, but relevant research among adolescents in China is presently limited. We conducted the present study to investigate the distribution of multi-dimensional self-rating biological rhythm disorder and the association of self-rating biological rhythm disorders with depression and anxiety symptoms among Chinese adolescents in different academic stages.

METHODS

In the cross-sectional study, 3693 students aged 11-23 from Zhengzhou City, Henan Province, China were included. The Patient Health Questionnaire (PHQ-9) and General Anxiety Disorder (GAD-7) were used to evaluate symptoms of depression and anxiety, respectively. Additionally, the Self-Rating of Biological Rhythm Disorder for Adolescents (SBRDA) was used to assess status of biological rhythm disorders. Multivariate logistic regression was developed to explore factors potentially associated with symptoms of depression and anxiety stratified by academic stages.

RESULTS

Among all participants, 44.14 and 36.15% suffered from depression and anxiety symptoms, respectively. On average, participants scored 74.66 ± 19.37 on the measure of total biological rhythm disorder. Adjusted for demographic confounding factors, the logistic regression analysis showed higher scores of total biological rhythm disorder were associated with more severe depression (OR = 14.38, 95%CI: 11.38-18.16) and anxiety symptoms (OR = 11.63, 95%CI: 9.14-14.81). The similar results were also found in the stratified analysis by academic stages.

CONCLUSIONS

Self-rating biological rhythm disorders are significantly associated with depression and anxiety symptoms among adolescents. Discrepancy across academic stages should also be taken into account in establishing public health strategies.

Bidirectional associations between nightly sleep and daily happiness and negative mood in adolescents

This study examined bidirectional associations between daily happiness and negative mood and subjective and objective sleep measures. Participants were 311 adolescents (M_age = 17.37 years; 51.8% female; 59.2% White/European American, 38.6% Black/African American, 1% Hispanic/Latinx American, 1.4% multi‐racial; 19.3% below poverty line) observed over a 7‐day period (2017–2018) using sleep diaries and actigraphy. Daily negative mood was related to greater subjective sleep/wake problems, and happiness was related to lower subjective sleep/wake problems. Conversely, shorter self‐reported sleep duration was related to higher negative mood the next day. For actigraphy measures, daily negative mood was related to greater sleep duration and efficiency, whereas happiness was related to lower sleep efficiency. Differences in associations based on subjective versus objective sleep measures are discussed.

Developmental features of sleep electrophysiology in family dogs

Age-related differences in dog sleep and the age at which dogs reach adulthood as indexed by sleep electrophysiology are unknown. We assessed, in (1) a Juvenile sample (n = 60) of 2-14-month-old dogs (weight range: 4-68 kg), associations between age, sleep macrostructure, and non-rapid eye movement (NREM) EEG power spectrum, whether weight moderates associations, and (2) an extended sample (n = 91) of 2-30-months-old dogs, when sleep parameters stabilise. In Juvenile dogs, age was positively associated with time in drowsiness between 2 and 8 months, and negatively with time in rapid eye movement (REM) sleep between 2 and 6 months. Age was negatively associated with delta and positively with theta and alpha power activity, between 8 and 14 months. Older dogs exhibited greater sigma and beta power activity. Larger, > 8-month-old dogs had less delta and more alpha and beta activity. In extended sample, descriptive data suggest age-related power spectrum differences do not stabilise by 14 months. Drowsiness, REM, and delta power findings are consistent with prior results. Sleep electrophysiology is a promising index of dog neurodevelopment; some parameters stabilise in adolescence and some later than one year. Determination of the effect of weight and timing of power spectrum stabilisation needs further inquiry. The dog central nervous system is not fully mature by 12 months of age.

Daily bidirectional associations between adolescent negative peer interactions and sleep in rural China: The moderating effect of parental migration

Left-behind adolescents' biobehavioral adjustment, such as sleep, is poorly understood by research. Using daily data over one week from 90 middle school students (M_age  = 13.69) in rural China, this study investigated daily bidirectional associations between negative peer interactions and sleep disturbances, and how these associations varied by parental migration. On days when adolescents reported higher levels of negative peer interactions, they also reported greater daytime dysfunction the following day. Conversely, when adolescents had more nighttime disturbances the previous night, they also reported higher levels of negative peer interactions. The effects of other sleep disturbance indicators (poor sleep quality the previous night and daytime dysfunction on the same day) on negative peer interactions were significant for adolescents with at least one parent migrating and for those with both parents migrating. Findings highlight the importance of considering dynamic interrelations between interpersonal and biobehavioral factors for the healthy development of left-behind adolescents.

The role of chronotype and reward processing in understanding social hierarchies in adolescence

INTRODUCTION

Circadian rhythms shift toward an evening preference during adolescence, a developmental period marked by greater focus on the social domain and salience of social hierarchies. The circadian system influences maturation of cognitive architecture responsible for motivation and reward, and observation of responses to reward cues has provided insights into neurocognitive processes that underpin adolescent social development. The objective was to investigate whether circadian phase of entrainment (chronotype) predicted both reward-related response inhibition and social status, and to explore whether mediator and moderator relationships existed between chronotype, reward processing, and social status outcomes.

METHODS

Participants were 75 adolescents aged 13-14 years old (41 females) who completed an eye tracking paradigm that involved an inhibitory control task (antisaccade task) within a nonsocial reward (Card Guessing Game) and a social reward (Cyberball Game) context. Chronotype was calculated from weekend midsleep and grouped into early, intermediate, and later terciles. Participants indicated subjective social status compared with peers in seven domains.

RESULTS

An intermediate and later chronotype predicted improved inhibitory control in the social versus nonsocial reward context. Chronotype also predicted higher perceived social status in two domains (powerful, troublemaker). Intermediate chronotypes reported higher "Powerful" status whereas later chronotypes were higher on "Troublemaker." Improved social reward-related performance predicted only the higher powerful scores and chronotype moderated this relationship. Improved inhibitory control to social reward predicted higher subjective social status in the intermediate and later chronotype group, an effect that was absent in the early group.

CONCLUSION

This behavioral study found evidence that changes toward a later phase of entrainment predicts social facilitation effects on inhibitory control and higher perceived power among peers. It is proposed here that circadian delayed phase in adolescence is linked to approach-related motivation, and the social facilitation effects could reflect a social cognitive capacity involved in the drive to achieve social rank.

Associations between sleep quality and psychological distress in early adolescence

Background: Although numerous studies have reported an association between sleep quality and mental health, few have focused on this association exclusively in early adolescence. Targeting this age group is vital as many mental illnesses first emerge during adolescence and remain a significant burden throughout life. Method: In the current study n = 60 participants aged 12 years completed the Pittsburgh Sleep Quality Index (PSQI) and Kessler Psychological Distress Scale (K10). Results: Consistent with previous findings, bivariate correlations revealed significant positive linear relationships between K10 total score and (i) PSQI total score; (ii) sleep quality; (iii) daytime dysfunction; and (iv) sleep disturbance. However, contrary to previous findings, there was no significant correlation between K10 scores and sleep duration. Conclusion: The association between sleep quality and psychological distress in early adolescents provides some important clues about the role that sleep may play in predicting the onset of anxiety and depressive disorders. Longitudinal studies should be undertaken to investigate age-related changes in sleep and psychological distress.

Self-reported sleep patterns and quality amongst adolescents: cross-sectional and prospective associations with anxiety and depression

BACKGROUND

Sleep problems are common in adolescence, and frequently comorbid with both anxiety and depression. Research studies have suggested a bidirectional relationship between sleep and psychopathology, which includes evidence that sleep interventions can alleviate symptoms of anxiety and depression. However, little is known about the nature of sleep problems amongst adolescents with anxiety and depression, and whether specific sleeping difficulties are involved in the longitudinal relationship between sleep, anxiety and depression.

METHOD

The sample was derived from the Avon Longitudinal Study of Parents and Children (ALSPAC), a population-based, prospective, birth cohort study of children born in 1991-1992. Data were explored from a subset of participants who took part in a clinical assessment at age 15, on self-report sleep patterns and quality, and diagnostic outcomes of anxiety and depression (N = 5,033). Subsequent diagnostic and symptom severity data on anxiety and depression at ages 17, 21 and 24 were also examined.

RESULTS

Cross-sectional and longitudinal analyses were conducted to explore the relationship between sleep problems, anxiety and depression. Results revealed that adolescents aged 15 with depression experience difficulties with both sleep patterns and sleep quality, whereas adolescents with anxiety only reported problems with sleep quality. A range of sleep variables at age 15 predicted the severity of anxiety and depression symptoms and the diagnoses of anxiety and depressive disorders at age 17, 21 and 24 years.

CONCLUSIONS

The results provide further insight into the nature of sleep problems amongst adolescents with anxiety and depression, and the prospective relationship between sleep disturbance and future psychopathology. These data suggest that targeting sleep difficulties during adolescence may have long-term mental health benefits.

Dietary Patterns in Relation to Prospective Sleep Duration and Timing among Mexico City Adolescents

Adult studies show that healthy diet patterns relate to better sleep. However, evidence during adolescence, when sleep may change dramatically, is lacking. Within a cohort of 458 Mexican adolescents, we examined whether consumption of three dietary patterns was associated with sleep duration and timing measured 2 years later, as well as changes in sleep timing and duration. Dietary patterns (identified a posteriori in a prior analysis) were assessed with a baseline food frequency questionnaire, and sleep was measured with wrist actigraphy at baseline and follow-up. Linear regression analyses adjusting for sex, age, screen time, and smoking were conducted. Adolescents with higher consumption of a Plant-Based and Lean Proteins pattern had earlier sleep timing (−0.45 h with 95% Confidence Interval (CI) −0.81, −0.08 in the highest compared to lowest quartiles), less of a phase delay in sleep timing over follow-up (−0.39 h with 95% CI −0.80, 0.02), and shorter weekend sleep duration (0.5 h with 95% CI −0.88, −0.1). Higher consumption of an Eggs, Milk and Refined Grain pattern was associated with earlier sleep timing (−0.40 h with 95% CI −0.77, −0.04), while consumption of a Meat and Starchy pattern was related to higher social jetlag (weekend–weekday sleep timing difference). Healthier diet patterns may promote better sleep in adolescents.

Sleep difficulties and suicidality in youth: current research and future directions

Studies have established a clear relationship between subjective sleep problems and the continuum of suicidality in adolescents. These studies are primarily cross-sectional in nature and conducted with epidemiological and depressed clinical samples. More recent studies focus on prospective data. Herein, we provide an update on current studies on the sleep-suicide association among youth. To further the critical mission of youth suicide prevention, future directions include more nuanced study of sleep employing a sleep health framework, longitudinal studies employing both objective and subjective sleep measures, fine-grained temporal associations between these constructs and their fluctuations over time, as well as enhanced understanding of the mechanisms underlying these associations.

Adiposity and Physical Activity Do Not Mediate the Longitudinal Association Between Sleep Quality and Arterial Thickness Among Adolescents

STUDY OBJECTIVES

Sleep is a behavior with the potential to affect cardiovascular health. Given the fact that adiposity and physical activity seem to be related to cardiovascular risk factors during growth, it is still unclear whether sleep quality could affect arterial thickness among adolescents. Thus, the objective of the current study was to analyze the effect of sleep quality on arterial thickness and identify the possible mediation role of physical activity and trunk fat in adolescents.

METHODS

This was a longitudinal study (12-month follow-up) composed of 71 adolescents with ages ranging from 11 to 14 years at baseline (absence of any known chronic diseases, and no regular medicine use). All variables were assessed twice (baseline and 12-month follow-up): (1) sleep quality was reported using the Mini Sleep Questionnaire (MSQ); (2) physical activity was estimated using pedometers; (3) trunk fat was assessed using a densitometry scanner; and (4) carotid intima-media thickness (CIMT) and femoral intima-media thickness (FIMT) were assessed using ultrasonography.

RESULTS

Adolescents who presented poor sleep quality demonstrated significantly increased FIMT (r = .299, 95% confidence interval .071 to .498) and for every point increase in the MSQ score from baseline to follow-up there was a 1.12% (95% confidence interval 0.26 to 1.98) increase in FIMT over time. Moreover, trunk fat and physical activity did not mediate the association between sleep quality and arterial thickness, but FIMT had a positive and independent relationship only with trunk fat.

CONCLUSIONS

Sleep quality was positively associated with FIMT among adolescents, whereas physical activity and adiposity did not mediate this process.

Stability of diurnal cortisol measures across days, weeks, and years across middle childhood and early adolescence: Exploring the role of age, pubertal development, and sex

Effective regulation of the hypothalamic-pituitary-adrenal axis (HPA-axis) has been linked to numerous health outcomes. Within-person variation in diurnal measures of HPA-axis regulation assessed over days, months, and years can range between 50-73% of total variation. In this study of 59 youth (ages 8-13), we quantified the stability of the cortisol awakening response (CAR), the diurnal slope, and tonic cortisol concentrations at waking and bedtime across 8 days (2 sets of 4 consecutive days separated by 3 weeks), 3 weeks, and 3 years. We then compared the stability of these indices across three key developmental factors: age, pubertal status, and sex. Youth provided 4 saliva samples per day (waking, 30 min post-waking, before dinner, and before bedtime) for 4 consecutive days during the 3rd week of an ongoing 8-week daily diary study. Youth repeated this same sampling procedure 3 weeks and 3 years later. Using multi-level modeling, we computed the amount of variance in diurnal HPA-axis regulation that was accounted for by nesting an individual's diurnal cortisol indices within days, weeks, or years. Across days, diurnal slope was the most stable index, whereas waking cortisol and CAR were the least stable. All indices except bedtime cortisol were similarly stable when measured across weeks, and all indices were uniformly stable when measured across 3 years. Boys, younger participants, and youth earlier in their pubertal development at study enrollment exhibited greater HPA-axis stability overall compared with females and older, more physically mature participants. We conclude that important within- and between-subjects questions can be answered about health and human development by studying HPA-axis regulation, and selection of the index of interest should be determined in part by its psychometric characteristics. To this end, we propose a decision tree to guide study design for research in pediatric samples by longitudinal timeframe and sample characteristics.

Patterns and Correlates of Self-Reported Physical Activity in a Cohort of Racially Diverse Pregnant Adolescents

STUDY OBJECTIVE

Regular physical activity (PA) during pregnancy decreases the risk of gestational hypertension and preeclampsia. Currently, little is known about the PA of pregnant adolescents. Our intent was to characterize the PA behaviors of a group of racially diverse, low-income pregnant teens and to identify potential determinants of PA.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTIONS

A cohort of 157 racially diverse pregnant adolescents (13-18 years of age) completed up to 3 previous day PA recalls as part of a larger prospective longitudinal study on determinants of maternal and fetal bone health. Subjects self-reported activities from 7 AM to 11:30 PM, choosing from a list of 37 activities including a category for "other." Subjects recorded activities in 30-minute intervals.

MAIN OUTCOME MEASURES

Estimated metabolic equivalent task (MET) values were assigned to each activity and summed for a measure of total daily PA in MET min/d. Determinants of PA were evaluated using a stepwise linear mixed effect model.

RESULTS

The average calculated MET min/d was 1478 ± 130. Significant determinants of MET min/d included race (P = .007), maternal age at conception (P = .042), gestational age (P = .002), and attending school (P < .001). Black teens were less physically active than white teens, and older teens were more active than younger teens; activity decreased throughout gestation, and teens currently attending school were more active.

CONCLUSION

PA is low across gestation and pregnant teens spent more than half of their monitored time in sedentary activities. Targeted interventions are needed to achieve current PA goals in this pediatric obstetric population.

Associations between active commuting to school, sleep duration, and breakfast consumption in Ecuadorian young people

BACKGROUND

Daily behaviours such as active commuting to school (ACS) could be a source of physical activity, contributing to the improvement of youth cardiovascular health, however, the relationship between ACS and other aspects of a youth's health, such as sleep duration and breakfast consumption, require further clarification. The aims of this study were therefore: 1) to analyse the prevalence of modes of commuting to school, sleep duration, and breakfast consumption by age groups and gender, and 2) to analyse the association between ACS, sleep duration recommendations, and breakfast consumption by age groups and gender.

METHOD

This cross-sectional study included 732 school-aged students of low-middle socioeconomic status, categorised into children (10-12 yr), young adolescents (13-15 yr), and older adolescents (16-18 yr). Modes of commuting to/from school, sleep duration, and breakfast consumption were self-reported. Logistic regression models were fitted to examine the association between ACS, sleep duration and breakfast consumption, analysed according to age groups and gender.

RESULTS

The percentage of students meeting sleep duration and daily breakfast recommendations was lowest in older adolescents, and highest in children (6.3% versus 50.8% p < 0.001, and 62.1%, versus 76.8%, p = 0.001, respectively). Young adolescents and girls who met the sleep duration recommendations were more likely to be active commuters than their counterparts (OR = 4.25; 95% CI = 1.81 to 9.92, p = 0.001 and OR = 2.89; 95%CI = 1.01 to 8.27, p = 0.04, respectively).

CONCLUSION

Young adolescents (13-15 yr) and girls who met the sleep duration recommendations during school days displayed a positive association with ACS. There was no association between ACS and breakfast consumption for any of the age groups or gender. Children (10-12 yr) were those that best meet with the adequate sleep duration and breakfast consumption recommendations.

Rhythms of life: circadian disruption and brain disorders across the lifespan

Many processes in the human body - including brain function - are regulated over the 24-hour cycle, and there are strong associations between disrupted circadian rhythms (for example, sleep-wake cycles) and disorders of the CNS. Brain disorders such as autism, depression and Parkinson disease typically develop at certain stages of life, and circadian rhythms are important during each stage of life for the regulation of processes that may influence the development of these disorders. Here, we describe circadian disruptions observed in various brain disorders throughout the human lifespan and highlight emerging evidence suggesting these disruptions affect the brain. Currently, much of the evidence linking brain disorders and circadian dysfunction is correlational, and so whether and what kind of causal relationships might exist are unclear. We therefore identify remaining questions that may direct future research towards a better understanding of the links between circadian disruption and CNS disorders.

Seasonal and weather variation of sleep and physical activity in 12-14-year-old children

Background: Understanding variation in physical activity (PA) and sleep is necessary to develop novel intervention strategies targeting adolescents' health behaviors. We examined the extent to which PA and sleep vary by aspects of the physical environment. Participants: We performed a cross-sectional analysis of 669 adolescents in the Project Viva cohort. Methods: We estimated total PA, sleep duration, sleep efficiency, and sleep midpoint timing from wrist accelerometers. We used multivariable linear regression models and generalized estimated equations to assess associations of PA and sleep with season and daily weather conditions obtained from the National Oceanic and Atmospheric Administration archive. Results: Mean age was 12.9 (SD 0.6) years; 51% were female and 68% were white. Mean sleep duration was 466 (SD 42) min per night and total PA was 1,652 (SD 431) counts per min per day. Sleep midpoint time was 41 (95% CI: 27 to 54) min later in summer, 28 (95% CI: -41 to -14) min earlier in spring, and 29 (95% CI: -43 to -15) min earlier in autumn compared to winter. Higher temperature and longer day length both were associated with small reductions of nightly sleep duration. Adolescents were less physically active during winter and on rainy and short sunlight days. There was an inverse U-shaped relationship between PA and mean temperature. Conclusions: Season was associated with large changes in sleep timing, and smaller changes in other sleep and PA measurements. Given the importance of sleep and circadian alignment, future health behavioral interventions may benefit by targeting "season-specific" interventions.

Melatonin, adolescence, and the brain: An insight into the period-specific influences of a multifunctional signaling molecule

Melatonin is a neurohormone that is involved in the modulation of a wide range of physiological processes, including maintenance of the circadian rhythm, mediation of photoperiodic information, regulation of the sleep-wake cycle, synchronization of cell physiology, antioxidant defense, and immune-modulation. Although there are reports of increasing use of melatonin in the management of a number of health conditions, evidence exists that is suggestive of deleterious effects of melatonin administration on brain and reproductive development in the prepubertal and pubertal periods that are within the teenage years. In this review, we examine the influences of endogenous and exogenous melatonin on the adolescent brain, with specific reference to its involvement in the evolution of brain functions, brain structure, sleep regulation, and modulation of behaviors in health or disease.

Electrophysiological Properties of Melanin-Concentrating Hormone and Orexin Neurons in Adolescent Rats

Orexin and melanin-concentrating hormone (MCH) neurons have complementary roles in various physiological functions including energy balance and the sleep/wake cycle. in vitro electrophysiological studies investigating these cells typically use post-weaning rodents, corresponding to adolescence. However, it is unclear whether these neurons are functionally mature at this period and whether these studies can be generalized to adult cells. Therefore, we examined the electrophysiological properties of orexin and MCH neurons in brain slices from post-weaning rats and found that MCH neurons undergo an age-dependent reduction in excitability, but not orexin neurons. Specifically, MCH neurons displayed an age-dependent hyperpolarization of the resting membrane potential (RMP), depolarizing shift of the threshold, and decrease in excitatory transmission, which reach the adult level by 7 weeks of age. In contrast, basic properties of orexin neurons were stable from 4 weeks to 14 weeks of age. Furthermore, a robust short-term facilitation of excitatory synapses was found in MCH neurons, which showed age-dependent changes during the post-weaning period. On the other hand, a strong short-term depression was observed in orexin neurons, which was similar throughout the same period. These differences in synaptic responses and age dependence likely differentially affect the network activity within the lateral hypothalamus where these cells co-exist. In summary, our study suggests that orexin neurons are electrophysiologically mature before adolescence whereas MCH neurons continue to develop until late adolescence. These changes in MCH neurons may contribute to growth spurts or consolidation of adult sleep patterns associated with adolescence. Furthermore, these results highlight the importance of considering the age of animals in studies involving MCH neurons.

Sleep Patterns and Quality Are Associated with Severity of Obesity and Weight-Related Behaviors in Adolescents with Overweight and Obesity

BACKGROUND

Inadequate sleep duration, sleep patterns, and sleep quality have been associated with metabolic, circadian, and behavioral changes that promote obesity. Adolescence is a period during which sleep habits change to include less sleep, later bedtimes, and greater bedtime shift (e.g., difference between weekend and weekday bedtime). Thus, sleep may play a role in adolescent obesity and weight-related behaviors. This study assesses sleep duration, quality, and schedules and their relationships to relative weight and body fat percentage as well as diet, physical activity, and screen time in adolescents with overweight/obesity.

METHODS

Adolescents between 12 and 17 years old (n = 186) were weighed and measured, reported typical sleep and wake times on weekdays and weekends, and responded to questionnaires assessing diet, physical activity, and screen time habits.

RESULTS

Controlling for sleep duration, later weekend bedtime and greater bedtime shift were associated with greater severity of overweight (β = 0.20; β = 0.16) and greater screen time use (β = 0.22; β = 0.2). Later bedtimes on the weekdays and weekends were associated with fewer healthy diet practices (β = -0.26; β = -0.27). In addition, poorer sleep quality was associated with fewer healthy diet habits (β = -0.21), greater unhealthy diet habits (β = 0.15), and less physical activity (β = -0.22). Sleep duration was not associated with any weight or weight-related behavior.

CONCLUSIONS

Sleep patterns and quality are associated with severity of overweight/obesity and various weight-related behaviors. Promoting a consistent sleep schedule throughout the week may be a worthwhile treatment target to optimize behavioral and weight outcomes in adolescent obesity treatment.

Restoring Serotonergic Homeostasis in the Lateral Hypothalamus Rescues Sleep Disturbances Induced by Early-Life Obesity

Early-life obesity predisposes to obesity in adulthood, a condition with broad medical implications including sleep disorders, which can exacerbate metabolic disturbances and disrupt cognitive and affective behaviors. In this study, we examined the long-term impact of transient peripubertal diet-induced obesity (ppDIO, induced between 4 and 10 weeks of age) on sleep-wake behavior in male mice. EEG and EMG recordings revealed that ppDIO increases sleep during the active phase but reduces resting-phase sleep quality. This impaired sleep phenotype persisted for up to 1 year, although animals were returned to a non-obesiogenic diet from postnatal week 11 onwards. To better understand the mechanisms responsible for the ppDIO-induced alterations in sleep, we focused on the lateral hypothalamus (LH). Mice exposed to ppDIO did not show altered mRNA expression levels of orexin and melanin-concentrating hormone, two peptides that are important for sleep-wake behavior and food intake. Conversely, the LH of ppDIO-exposed mice had reduced contents of serotonin (5-hydroxytryptamine, 5-HT), a neurotransmitter involved in both sleep-wake and satiety regulation. Interestingly, an acute peripheral injection of the satiety-signaling peptide YY 3-36 increased 5-HT turnover in the LH and ameliorated the ppDIO-induced sleep disturbances, suggesting the therapeutic potential of this peptide. These findings provide new insights into how sleep-wake behavior is programmed during early life and how peripheral and central signals are integrated to coordinate sleep.SIGNIFICANCE STATEMENT Adult physiology and behavior are strongly influenced by dynamic reorganization of the brain during puberty. The present work shows that obesity during puberty leads to persistently dysregulated patterns of sleep and wakefulness by blunting serotonergic signaling in the lateral hypothalamus. It also shows that pharmacological mimicry of satiety with peptide YY_3-36 can reverse this neurochemical imbalance and acutely restore sleep composition. These findings add insight into how innate behaviors such as feeding and sleep are integrated and suggest a novel mechanism through which diet-induced obesity during puberty imposes its long-lasting effects on sleep-wake behavior.

The mediating role of cortical thickness and gray matter volume on sleep slow-wave activity during adolescence

During the course of adolescence, reductions occur in cortical thickness and gray matter (GM) volume, along with a 65% reduction in slow-wave (delta) activity during sleep (SWA) but empirical data linking these structural brain and functional sleep differences, is lacking. Here, we investigated specifically whether age-related differences in cortical thickness and GM volume and cortical thickness accounted for the typical age-related difference in slow-wave (delta) activity (SWA) during sleep. 132 healthy participants (age 12-21 years) from the National Consortium on Alcohol and NeuroDevelopment in Adolescence study were included in this cross-sectional analysis of baseline polysomnographic, electroencephalographic, and magnetic resonance imaging data. By applying mediation models, we identified a large, direct effect of age on SWA in adolescents, which explained 45% of the variance in ultra-SWA (0.3-1 Hz) and 52% of the variance in delta-SWA (1 to <4 Hz), where SWA was lower in older adolescents, as has been reported previously. In addition, we provide evidence that the structure of several, predominantly frontal, and parietal brain regions, partially mediated this direct age effect, models including measures of brain structure explained an additional 3-9% of the variance in ultra-SWA and 4-5% of the variance in delta-SWA, with no differences between sexes. Replacing age with pubertal status in models produced similar results. As reductions in GM volume and cortical thickness likely indicate synaptic pruning and myelination, these results suggest that diminished SWA in older, more mature adolescents may largely be driven by such processes within a number of frontal and parietal brain regions.

Sleep restriction in Wistar rats impairs epididymal postnatal development and sperm motility in association with oxidative stress

Good sleep quality has a direct effect on the activity of the neuroendocrine–reproductive control axis and oxidative stress. Thus, the aim of the present study was to evaluate whether sleep restriction (SR) during the peripubertal period impaired the postnatal development of the epididymis in Wistar rats. After 21 days SR (18 h per day), epididymides were collected on Postnatal Day (PND) 62 for evaluation of oxidative stress markers, inflammatory profile, sperm count and histopathological and stereological analyses; in addition, the motility of spermatozoa from the vas deferens was examined. SR significantly increased lipid peroxidation and glutathione levels in the caput and cauda epididymidis, and increased levels of total radical-trapping antioxidant potential in the caput epididymidis only. Neutrophil migration to the caput or corpus epididymidis was decreased by SR, and the size of the luminal compartment in the 2A region and the epithelial compartment in the 5A/B region was also decreased. In these regions, there was an increase in the size of the interstitial compartment. The percentage of immotile spermatozoa was higher in the SR group. In conclusion, SR affects epididymal postnatal development, as well as sperm motility, in association with increased oxidative stress and a decrease in the size of the epithelial compartment in the cauda epididymidis.

EEG Changes across Multiple Nights of Sleep Restriction and Recovery in Adolescents: The Need for Sleep Study

STUDY OBJECTIVES

To investigate sleep EEG changes in adolescents across 7 nights of sleep restriction to 5 h time in bed [TIB]) and 3 recovery nights of 9 h TIB.

METHODS

A parallel-group design, quasi-laboratory study was conducted in a boarding school. Fifty-five healthy adolescents (25 males, age = 15-19 y) who reported habitual TIBs of approximately 6 h on week nights (group average) but extended their sleep on weekends were randomly assigned to Sleep Restriction (SR) or Control groups. Participants underwent a 2-week protocol comprising 3 baseline nights (TIB = 9 h), 7 nights of sleep opportunity manipulation (TIB = 5 h for the SR and 9 h for the Control group), and 3 nights of recovery sleep (TIB = 9 h). Polysomnography was obtained on two baseline, three manipulation, and two recovery nights.

RESULTS

Across the sleep restriction nights, total SWS duration was preserved relative to the 9 h baseline sleep opportunity, while other sleep stages were reduced. Considering only the first 5 h of sleep opportunity, SR participants had reduced N1 duration and wake after sleep onset (WASO), and increased total sleep time (TST), rapid eye movement (REM) sleep, and slow wave sleep (SWS) relative to baseline. Total REM sleep, N2, and TST duration remained above baseline levels by the third recovery sleep episode.

CONCLUSIONS

In spite of preservation of SWS duration over multiple nights of sleep restriction, adolescents accustomed to curtailing nocturnal sleep on school day nights evidence residual effects on sleep macro-structure, even after three nights of recovery sleep. Older teenagers may not be as resilient to successive nights of sleep restriction as is commonly believed.

Sleep efficiency as a determinant of insulin sensitivity in overweight and obese adolescents

Insulin resistance (IR) occurs in a transient manner during puberty. Obese adolescents may be at risk for persistent IR during puberty. The objective of the study is to review the literature on the association of the anthropometry and lifestyle characteristics with insulin sensitivity in overweight and obese adolescents, and include data from a new study. Relevant papers were selected and reviewed. In addition, 137 overweight and obese adolescents (42 male/95 female, age 14.4 ± 2.3 years, BMI z-score +3.3 ± 0.7, HOMA-IR 3.4 ± 1.8) from the Centre for Overweight Adolescent and Children's Healthcare (MUMC+) were included in this study. Anthropometrics, Tanner stages, sleep characteristics, food intake behaviour and physical activity were determined, and possible associations with homeostasis model assessment of insulin resistance (HOMA-IR) were tested.

RESULTS

Overweight and obese adolescents with unfavourable fat partitioning and family history of NIDDM are at risk for persistent IR. Overweight and obese adolescents from the new cohort showed a higher HOMA-IR postpubertally. BMI z-score, age, pubertal stage and prepubertally total sleeping time (TST) and sleep efficiency (SE) were identified as significant contributors. Overweight and obese adolescents showed a persistently higher instead of transiently higher HOMA-IR during puberty, associated with BMI z-score, age, pubertal stage and prepubertally less TST and SE.

The Effect of Adenotonsillectomy for Childhood Sleep Apnea on Cardiometabolic Measures

STUDY OBJECTIVES

Obstructive sleep apnea syndrome (OSAS) has been associated with cardiometabolic disease in adults. In children, this association is unclear. We evaluated the effect of early adenotonsillectomy (eAT) for treatment of OSAS on blood pressure, heart rate, lipids, glucose, insulin, and C-reactive protein. We also analyzed whether these parameters at baseline and changes at follow-up correlated with polysomnographic indices.

DESIGN

Data collected at baseline and 7-mo follow-up were analyzed from a randomized controlled trial, the Childhood Adenotonsillectomy Trial (CHAT).

SETTING

Clinical referral setting from multiple centers.

PARTICIPANTS

There were 464 children, ages 5 to 9.9 y with OSAS without severe hypoxemia.

INTERVENTIONS

Randomization to eAT or Watchful Waiting with Supportive Care (WWSC).

MEASUREMENTS AND RESULTS

There was no significant change of cardiometabolic parameters over the 7-mo interval in the eAT group compared to WWSC group. However, overnight heart rate was incrementally higher in association with baseline OSAS severity (average heart rate increase of 3 beats per minute [bpm] for apnea-hypopnea index [AHI] of 2 versus 10; [standard error = 0.60]). Each 5-unit improvement in AHI and 5 mmHg improvement in peak end-tidal CO2 were estimated to reduce heart rate by 1 and 1.5 bpm, respectively. An increase in N3 sleep also was associated with small reductions in systolic blood pressure percentile.

CONCLUSIONS

There is little variation in standard cardiometabolic parameters in children with obstructive sleep apnea syndrome (OSAS) but without severe hypoxemia at baseline or after intervention. Of all measures, overnight heart rate emerged as the most sensitive parameter of pediatric OSAS severity.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov (#NCT00560859).

Sleep/Wake Dynamics Changes during Maturation in Rats

Objectives

Conventional scoring of sleep provides little information about the process of transitioning between vigilance states. We applied the state space technique (SST) using frequency band ratios to follow normal maturation of different sleep/wake states, velocities of movements, and transitions between states of juvenile (postnatal day 34, P34) and young adult rats (P71).

Design

24-h sleep recordings of eight P34 and nine P71 were analyzed using conventional scoring criteria and SST one week following implantation of telemetric transmitter. SST is a non-categorical approach that allows novel quantitative and unbiased examination of vigilance-states dynamics and state transitions. In this approach, behavioral changes are described in a 2-dimensional state space that is derived from spectral characteristics of the electroencephalography.

Measurements and Results

With maturation sleep intensity declines, the duration of deep slow wave sleep (DSWS) and light slow wave sleep (LSWS) decreases and increases, respectively. Vigilance state determination, as a function of frequency, is not constant; there is a substantial shift to higher ratio 1 in all vigilance states except DSWS. Deep slow wave sleep decreases in adult relative to juvenile animals at all frequencies. P71 animals have 400% more trajectories from Wake to LSWS (p = 0.005) and vice versa (p = 0.005), and 100% more micro-arousals (p = 0.021), while trajectories from LSWS to DSWS (p = 0.047) and vice versa (p = 0.033) were reduced by 60%. In both juvenile and adult animals, no significant changes were found in sleep velocity at all regions of the 2-dimensional state space plot; suggesting that maturation has a partial effect on sleep stability.

Conclusions

Here, we present novel and original evidence that SST enables visualization of vigilance-state intensity, transitions, and velocities that were not evident by traditional scoring methods. These observations provide new perspectives in sleep state dynamics and highlight the usefulness of this technique in exploring the development of sleep-wake activity.

Sleep and Early Cortical Development

Sleep is increasingly recognized as a key process in neurodevelopment. Animal data show that sleep is essential for the maturation of fundamental brain functions, and growing epidemiological findings indicate that children with early sleep disturbance suffer from later cognitive, attentional, and psychosocial problems. Still, major gaps exist in understanding processes underlying links between sleep and neurodevelopment. One challenge is to translate findings from animal research to humans. In this review, we describe parallels and differences in sleep and development of the cortex in humans and animals and discuss emerging questions.

Mathematical models for sleep-wake dynamics: comparison of the two-process model and a mutual inhibition neuronal model

Sleep is essential for the maintenance of the brain and the body, yet many features of sleep are poorly understood and mathematical models are an important tool for probing proposed biological mechanisms. The most well-known mathematical model of sleep regulation, the two-process model, models the sleep-wake cycle by two oscillators: a circadian oscillator and a homeostatic oscillator. An alternative, more recent, model considers the mutual inhibition of sleep promoting neurons and the ascending arousal system regulated by homeostatic and circadian processes. Here we show there are fundamental similarities between these two models. The implications are illustrated with two important sleep-wake phenomena. Firstly, we show that in the two-process model, transitions between different numbers of daily sleep episodes can be classified as grazing bifurcations. This provides the theoretical underpinning for numerical results showing that the sleep patterns of many mammals can be explained by the mutual inhibition model. Secondly, we show that when sleep deprivation disrupts the sleep-wake cycle, ostensibly different measures of sleepiness in the two models are closely related. The demonstration of the mathematical similarities of the two models is valuable because not only does it allow some features of the two-process model to be interpreted physiologically but it also means that knowledge gained from study of the two-process model can be used to inform understanding of the behaviour of the mutual inhibition model. This is important because the mutual inhibition model and its extensions are increasingly being used as a tool to understand a diverse range of sleep-wake phenomena such as the design of optimal shift-patterns, yet the values it uses for parameters associated with the circadian and homeostatic processes are very different from those that have been experimentally measured in the context of the two-process model.

The relationship between sleep disorders and testosterone

PURPOSE OF REVIEW

This review describes evolving concepts and recent data on the relationship between serum testosterone levels and normal and disordered sleep.

RECENT FINDINGS

Sex-related differences in circadian rhythms and sleep physiology are in part due to organizational and activational effects of sex steroids. Testosterone affects the organization of circadian rhythms and the timing, but not the duration, of sleep. Increasing testosterone during puberty leads to later bedtimes. The diurnal variation in testosterone depends on sleep rather than circadian rhythm or season. Pubertal onset is heralded, well before virilization, by a luteinizing hormone level at least 3.7 U/l during sleep. Total sleep deprivation lowers testosterone, but sleep restriction only does so if it occurs in the first half of the night. The recovery of testosterone from sleep disruption is impaired in old as compared with young rodents. In men with obstructive sleep apnoea (OSA), low testosterone is related to obesity rather than the OSA itself, and improves with weight loss but inconsistently with continuous positive airway pressure (CPAP). Testosterone treatment only transiently worsens severity of OSA, which need not be considered a contraindication to its use.

SUMMARY

Testosterone treatment is unlikely to benefit sleep in men with secondary hypogonadism, for example due to obesity or depression, in contrast to the management of the underlying abnormality.