Actigraphy-assessed sleep during school and vacation periods: a naturalistic study of restricted and extended sleep opportunities in adolescents

Daily fluctuations in adolescents' sleep predict next-day attention, sleepiness, and fatigue: an ecological momentary assessment study over 28 days

BACKGROUND

Current understanding of the associations between adolescents' daily sleep and daytime alertness and fatigue under naturalistically occurring restricted (school) and unrestricted (vacation) sleep opportunities is limited.

METHODS

A convenience sample of adolescents (n = 205; 54.1% females, Mage ± SD = 16.9 ± 0.87 years) completed daily measures of sleep, alertness, and fatigue over 28 days (2 weeks during school, and the subsequent 2-week vacation). Actigraphy and sleep diary total sleep time (TST) and sleep efficiency (SE) were measured. Participants self-reported sleepiness and fatigue every morning and afternoon, and completed a tablet-based, 3.2-min psychomotor vigilance task (PVT) every afternoon. Cross-lagged multilevel models tested daily TST and SE as predictors of next-day subjective sleepiness/fatigue and PVT performance. Between- (i.e., differences between individuals) and within-person associations (i.e., whether nights with higher-than-individual's-average TST/SE, predict next-day outcomes) were tested simultaneously. Covariates included previous-day outcome, day of the week, study day (1-28), school/vacation, chronotype, and sociodemographic variables.

RESULTS

Within-persons, higher-than-average TST and SE (both actigraphy and diary) predicted better next-day PVT performance (all p ≤ .006), and lower subjective sleepiness and fatigue the following morning and afternoon (all p ≤ .032). Between-persons, adolescents with higher overall diary SE had lower morning subjective sleepiness (p < .001) and fewer PVT false starts in the afternoon (p = 0.02).

CONCLUSIONS

Nights with longer- and higher-than-average sleep efficiency (both actigraphy and diary) predicted better daytime alertness and fatigue, both when examined objectively via sustained attention and via self-report. These findings are relevant for understanding the significance of sleep for adolescents' day-to-day alertness levels and fatigue, particularly in the context of classroom learning and road safety.

What helps and what hurts adolescents' sleep? An intense longitudinal ecological momentary assessment of daily facilitators and barriers of sleep on school and non-school nights

OBJECTIVE

Using an intense longitudinal design, we investigated adolescents' perceptions of everyday factors facilitating (i.e., facilitators) and hindering (i.e., barriers) sufficient and good quality sleep.

METHOD

Adolescents (N = 205, Mage = 16.9 ± 0.9, 54.1 % female, 64.4 % non-white) completed daily morning surveys, assessing self-reported sleep and the use of 8 facilitators and 6 barriers of sleep from the previous night, and wore actigraphs over 2 school-weeks followed by 2 vacation-weeks (5162 total observations). Linear mixed-effects models examined the contribution of facilitators/barriers to actigraphy and self-reported total sleep time (TST) and sleep onset latency (SOL), controlling for age, sex, race, and study day. School/non-school day status was included as a moderator.

RESULTS

Seven facilitators and two barriers were reported by >30 % of adolescents as frequently (≥50 % nights) helping/preventing them from achieving good sleep. Facilitators or barriers explained 1-5% (p-values <.001) of unique variance above and beyond the covariates. Facilitators that predicted better sleep were: following body cues, managing thoughts and emotions, creating good sleep environment, avoiding activities interfering with sleep, and bedtime planning (only TST on school nights). Barriers that predicted worse sleep were: pre-bed thoughts and emotions, unconducive sleep environment, activities interfering with sleep, inconsistent routines, and other household members' activities.

CONCLUSION

Adolescents use a range of sleep-facilitating behaviours, and a number of factors prevent sufficient and good quality sleep in their everyday life. These factors are predictive of their sleep duration and onset latency and require further research to understand their functions and clinical implications.

Variability of excessive daytime sleepiness and cataplexy according to seasonality: A study in central disorders of hypersomnolence

Seasonality of excessive daytime sleepiness has been proposed, yet no research has specifically investigated its impact on daytime sleepiness and cataplexy in central disorders of hypersomnolence. This study examined seasonal variations in daytime sleepiness and cataplexy in narcolepsy type 1, narcolepsy type 2 and idiopathic hypersomnia. Patients included in the study were on stable pharmacological treatment, and participated in sleep medicine interviews to assess diurnal sleepiness and daytime napping and completed the Epworth Sleepiness Scale to assess excessive daytime sleepiness (Epworth Sleepiness Scale ≥ 10). Patients with narcolepsy type 1 also maintained a cataplexy diary. Evaluations were conducted in autumn, winter, spring and summer. The study included 29 patients with narcolepsy type 1, 16 patients with narcolepsy type 2 and 10 patients with idiopathic hypersomnia. Patients with narcolepsy type 1 and narcolepsy type 2 showed higher Epworth Sleepiness Scale scores in summer compared with other seasons, while patients with idiopathic hypersomnia showed no changes in excessive daytime sleepiness across the four seasons. Epworth Sleepiness Scale scores were higher in idiopathic hypersomnia patients compared to narcolepsy type 1 and narcolepsy type 2 patients in spring, autumn, and winter; conversely, in summer there were no differences in Epworth Sleepiness Scale scores among the three groups. No significant differences in Epworth Sleepiness Scale scores were noted between patients with narcolepsy type 1 and narcolepsy type 2 throughout the year. Furthermore, no seasonal effect on cataplexy frequency was found in patients with narcolepsy type 1. This study demonstrates that seasonality may influence daytime sleepiness in patients with narcolepsy type 1 and narcolepsy type 2 but not in patients with idiopathic hypersomnia, while cataplexy symptoms remain unaffected by seasonal changes. The underlying mechanisms linking excessive daytime sleepiness to seasonality have yet to be explored, though social factors and vacation time may contribute to increased excessive daytime sleepiness in narcolepsy.

Perceptions around sleep hygiene practices and beliefs among urban Black adolescents and their caregivers during the COVID-19 pandemic

OBJECTIVE

This study gathered adolescent and caregiver perspectives on sleep hygiene practices and beliefs for Black families living in low-resourced urban communities.

METHODS

Semistructured interviews were conducted with adolescents (n = 9) and caregivers (n = 9) from January-March 2021, during the COVID-19 pandemic. Interview questions included adolescent's current sleep habits, barriers, and home and neighborhood influences. Trained researchers coded data using inductive analysis and a constant comparative method to derive themes.

RESULTS

Two themes focused on sleep hygiene practices, including items used to facilitate sleep (e.g., melatonin, electronics) and COVID-19 consequences on sleep schedules. Two themes focused on sleep hygiene beliefs, including a common value on the importance of sleep and influences on caregiver's bedtime rules.

CONCLUSIONS

Findings provide important insights on sleep hygiene practices and beliefs in a historically marginalized population of Black adolescents and caregivers in urban communities to inform targeted sleep interventions, policies, and programs for optimal sleep and well-being.

Morningness-Eveningness Preference and Motor Wake-Sleep Inertia in Adolescents

The aim of the present work was to analyze possible differences in the wake-sleep and sleep-wake transition in relation to adolescents' circadian preference using actigraphy. Overall, 729 participants were enrolled in the research and 443 of them wore actigraphs on the non-dominant wrist for at least three nights. According to the reduced Morningness-Eveningness Questionnaire for Children and Adolescents cut-off scores, 61 participants belonged to the evening-type category, while 38 participants belonged to the morning-type. We extracted the motor activity counts, minute-by-minute, during the wake-sleep and sleep-wake transitions, to depict the motor wake inertia and motor sleep inertia, respectively. We adopted the functional linear modeling statistical framework to examine the changes in both transitions according to chronotype. Overall, the results show a significantly higher motor wake inertia and lower motor sleep inertia in morning compared to evening types.

Seasonal and Weekly Patterns of Korean Adolescents' Web Search Activity on Insomnia: Retrospective Study

BACKGROUND

Sleep deprivation in adolescents is a common but serious public health issue. Adolescents often have a progressive circadian delay and suffer from insufficient sleep during weekdays due to the school schedule. Temporal patterns in internet search activity data can provide relevant information for understanding the characteristic sleep problems of the adolescent population.

OBJECTIVE

We aimed to reveal whether adolescents exhibit distinct temporal seasonal and weekly patterns in internet search activity on insomnia compared to adults.

METHODS

We hypothesized that adolescents exhibit larger variations in the internet search volume for insomnia, particularly in association with the school schedule (e.g., academic vacations and weekends). We extracted the daily search volume for insomnia in South Korean adolescents (13-18 years old), adults (19-59 years old), and young adults (19-24 years old) during the years 2016-2019 using NAVER DataLab, the most popular search engine in South Korea. The daily search volume data for each group were normalized with the annual median of each group. The time series of the search volume was decomposed into slow fluctuation (over a year) and fast fluctuation (within a week) using fast Fourier transform. Next, we compared the normalized search volume across months in a year (slow fluctuation) and days in a week (fast fluctuation).

RESULTS

In the annual trend, 2-way ANOVA revealed a significant (group) × (month) interaction (P<.001). Adolescents exhibited much greater seasonal variations across a year than the adult population (coefficient of variation=0.483 for adolescents vs 0.131 for adults). The search volume for insomnia in adolescents was notably higher in January, February, and August, which are academic vacation periods in South Korea (P<.001). In the weekly pattern, 2-way ANOVA revealed a significant (group) × (day) interaction (P<.001). Adolescents showed a considerably increased search volume on Sunday and Monday (P<.001) compared to adults. In contrast, young adults demonstrated seasonal and weekly patterns similar to adults.

CONCLUSIONS

Adolescents demonstrate distinctive seasonal and weekly patterns in internet searches on insomnia (ie, increased search in vacation months and weekend-weekday transitions), which are closely associated with the school schedule. Adolescents' sleep concerns might be potentially affected by the disrupted daily routine and the delayed sleep phase during vacations and weekends. As we demonstrated, comparing various age groups in infodemiology and infoveillance data might be helpful in identifying distinctive features in vulnerable age groups.

Are Adolescent Athletes Sleeping Enough? An Observational Study of Sleep Parameters during Schooldays and Holidays

Background: Inconsistent sleep schedules, frequent awakening after sleep onset (WASO), and decreased sleep efficiency (SE) are common issues among adolescent team sports athletes. Moreover, research indicates that sleep problems are enhanced across schooldays. The aim of the present study was to assess sleep patterns of adolescent athletes and compare sleep parameters between schooldays and holidays. Methods: The chronotype and sleep quality of twelve adolescent basketball players (mean age: 15.58 ± 0.67 years) were assessed. Objective sleep parameters were then analyzed using actigraphy over a 12-day period, which included six days during the school period and six days during holidays. Results: Data showed that total sleep time (TST), SE, and WASO (382.48 min, 81.81%, and 66.70 min, respectively) did not meet international recommendations for sleep quantity and quality. During school weekdays, time in bed (TIB), TST, and SE significantly decreased compared to weekends (p < 0.001, d = -1.49; p < 0.001, d = -1.64; and p = 0.01, d = -0.89, respectively). On weekdays, TIB, TST, and WASO were significantly lower on schooldays compared to holidays (p < 0.001, d = -1.83; p < 0.01, d = -1.01; and p = 0.02, d = -0.77, respectively). While no significant difference was observed in social jetlag, the mid-point of sleep was significantly later on holiday weekdays compared to school weekdays (p < 0.05, d = 0.65). Conclusions: Adolescent athletes experience insufficient sleep, especially on school weekdays, which is partially improved during weekends and holidays. Although sleep duration was longer during holidays, our results suggest that adolescent athletes' sleep was more fragmented. Consequently, it remains crucial to implement strategies to enhance their sleep health (e.g., napping).

Sleep and lucid dreaming in adolescent athletes and non-athletes

During lucid dreaming (LD), dreamers are aware of experiencing a dream and may consciously influence its content. This study used an online questionnaire to investigate the LD frequency and applications in 193 adolescent athletes and non-athletes (17.40 ± 2.09 years; 46% athletes, 54% controls). Given the critical role that sleep plays in adolescent health, development, and performance, associations of LD with various sleep parameters were also explored. LD is prominent in adolescents (67.4% experienced it at least once, 30.0% once a month or more, 12.9% at least once a week), but similar in terms of frequency and uses between athletes and non-athletes. A higher proportion of those who practiced sports/dance during LD reported improved waking self-efficacy (57.1%) over sport performance (42.9%). There was no indication that chronotype preference may influence LD nor that LD may be detrimental to adolescent sleep. Athletes and controls had similar sleep durations, daytime sleepiness, and sleep disturbances frequency, but athletes reported higher sleep quality. Despite, on average, meeting the minimum sleep recommendation guidelines for their age, a relatively large proportion of adolescents did not attain sufficient sleep, particularly on weeknights (47.4% 14-17 years; 20.0% 18-21 years), suggesting that restricted sleep remains prevalent in adolescent populations.

Examining the Bidirectional Associations Between Sleep Duration, Screen Time, and Internalizing Symptoms in the ABCD Study

PURPOSE

The likelihood of meeting sleep duration and screen time guidelines decreases as children develop toward adolescence. Simultaneously, the prevalence of internalizing symptoms increases. The purpose of this paper was to examine the bidirectional associations between sleep duration and screen time with internalizing symptoms in a one-year longitudinal study starting in late childhood.

METHODS

Participants were 10,828 youth (47.8% female) enrolled in the Adolescent Brain Cognitive Development Study. At baseline (mean age 9.9 years) and one-year follow-up (mean age 10.9 years), youth self-reported screen time for weekdays and weekend days. Responses were separately dichotomized as >2 versus ≤2 hours/day (meeting behavioral guidelines). Caregiver-reported youth sleep duration was dichotomized as <9 versus 9-11 hours/night (meeting behavioral guidelines). Caregivers reported internalizing symptoms via the child behavior checklist. The withdrawn/depressed, anxious/depressed, and somatic symptom child behavior checklist subscale t-scores were separately dichotomized as ≥65 (borderline clinical levels of symptoms and above) versus <65. Analyses were gender-stratified.

RESULTS

In females, longer baseline sleep duration was protective against withdrawn/depressed symptoms (odds ratio [OR] 0.6, 95% confidence interval [CI] 0.4-0.8) and somatic complaints (OR 0.8, 95% CI 0.6-0.97) one year later. In females, greater baseline weekend screen time was associated with increased risk of withdrawn/depressed symptoms (OR 1.6, 95% CI 1.1-2.2) one year later. No other significant associations were observed.

DISCUSSION

Longitudinal associations between sleep duration, weekend screen time, and internalizing symptoms were unidirectional (behavior preceding internalizing symptoms), among females only, and specific to withdrawn/depressed and somatic symptoms. These prospective study findings warrant attention and inform future research in this cohort.

Report from a randomized control trial: improved alignment between circadian biology and sleep-wake behavior as a mechanism of depression symptom improvement in evening-type adolescents with depressive symptoms

STUDY OBJECTIVES

An evening circadian preference is common among adolescents. It is characterized by a behavioral predilection for later sleep and wake timing and is associated with higher rates of Major Depressive Disorder (MDD). The present study aims to (a) test the effectiveness of a cognitive behavioral sleep intervention (Transdiagnostic Sleep and Circadian Intervention; TranS-C) in a sample of adolescents with an evening circadian preference and clinically significant depressive symptoms and (b) evaluate improved alignment between circadian biology and sleep-wake behavior as a potential mechanism in the relationship between sleep and depression symptom improvement.

METHODS

Adolescents with an evening circadian preference and clinically significant depressive symptoms were randomized to receive TranS-C (n = 24) or a psychoeducation condition (PE; n = 18). Alignment between circadian biology and sleep-wake behavior was measured using objective biological measurement. Measures of sleep and circadian rhythm were taken at pre- and posttreatment, and depression symptoms were measured at pre- and posttreatment and 6- and 12-month follow-up.

RESULTS

Mixed effects modeling revealed that compared with an active control condition, TranS-C resulted in a significant reduction in MDD severity at 12-month follow-up. A MacArthur mediation analysis conducted to explore alignment between circadian biology and sleep-wake behavior as a mediator of depression severity reduction through 12-month follow-up revealed a significant interaction between change in alignment between circadian biology and sleep-wake behavior and treatment arm, indicating that improved alignment between circadian biology and sleep-wake behavior at posttreatment was associated with improvements in depression outcomes at 12-month follow-up under the treatment condition.

CONCLUSIONS

These results provide novel evidence for improved alignment between circadian biology and sleep-wake behavior as a specific mechanism of depression improvement, provide key clues into the complex relationship between sleep and depression, and have significant clinical implications for adolescents with depression.

Effects of emerging alcohol use on developmental trajectories of functional sleep measures in adolescents

STUDY OBJECTIVES

Adolescence is characterized by significant brain development, accompanied by changes in sleep timing and architecture. It also is a period of profound psychosocial changes, including the initiation of alcohol use; however, it is unknown how alcohol use affects sleep architecture in the context of adolescent development. We tracked developmental changes in polysomnographic (PSG) and electroencephalographic (EEG) sleep measures and their relationship with emergent alcohol use in adolescents considering confounding effects (e.g. cannabis use).

METHODS

Adolescents (n = 94, 43% female, age: 12-21 years) in the National Consortium on Alcohol and Neurodevelopment in Adolescence (NCANDA) study had annual laboratory PSG recordings across 4-years. Participants were no/low drinkers at baseline.

RESULTS

Linear mixed effect models showed developmental changes in sleep macrostructure and EEG, including a decrease in slow wave sleep and slow wave (delta) EEG activity with advancing age. Emergent moderate/heavy alcohol use across three follow-up years was associated with a decline in percentage rapid eye movement (REM) sleep over time, a longer sleep onset latency (SOL) and shorter total sleep time (TST) in older adolescents, and lower non-REM delta and theta power in males.

CONCLUSIONS

These longitudinal data show substantial developmental changes in sleep architecture. Emergent alcohol use during this period was associated with altered sleep continuity, architecture, and EEG measures, with some effects dependent on age and sex. These effects, in part, could be attributed to the effects of alcohol on underlying brain maturation processes involved in sleep-wake regulation.

Measuring light regularity: sleep regularity is associated with regularity of light exposure in adolescents

STUDY OBJECTIVES

Light is the main time cue for the human circadian system. Sleep and light are intrinsically linked; light exposure patterns can influence sleep patterns and sleep can influence light exposure patterns. However, metrics for quantifying light regularity are lacking, and the relationship between sleep and light regularity is underexplored. We developed new metrics for light regularity and demonstrated their utility in adolescents, across school term and vacation.

METHODS

Daily sleep/wake and light patterns were measured using wrist actigraphy in 75 adolescents (54% male, 17.17 ± 0.83 years) over 2 weeks of school term and a subsequent 2-week vacation. The Sleep Regularity Index (SRI) and social jetlag were computed for each 2-week block. Light regularity was assessed using (1) variation in mean daily light timing (MLiT); (2) variation in daily photoperiod; and (3) the Light Regularity Index (LRI). Associations between SRI and each light regularity metric were examined, and within-individual changes in metrics were examined between school and vacation.

RESULTS

Higher SRI was significantly associated with more regular LRI scores during both school and vacation. There were no significant associations of SRI with variation in MLiT or daily photoperiod. Compared to school term, all three light regularity metrics were less variable during the vacation.

CONCLUSIONS

Light regularity is a multidimensional construct, which until now has not been formally defined. Irregular sleep patterns are associated with lower LRI, indicating that irregular sleepers also have irregular light inputs to the circadian system, which likely contributes to circadian disruption.

The impact of the COVID-19 pandemic on adolescent sleep behavior

Restorative sleep is a fundamental component of adolescent wellbeing, and the COVID-19 pandemic presented both challenges and opportunities for adolescents' sleep. In this review, we synthesize emergent themes from the growing scientific evidence for the impact of the pandemic on adolescent sleep behavior across different stages of the pandemic and in different locations around the world. We also highlight the ways in which COVID-19 shaped sleep patterns among college students-a subgroup of adolescents transitioning to emerging adulthood that were particularly impacted by the shift to remote learning. Finally, we discuss variations in the impact according to several potential moderating factors in adolescents' lives and point to areas that require additional longitudinal research.

Children's activity and diet behaviours in the summer holidays versus school year

BACKGROUND

Evidence shows children gain more weight during the summer holidays versus the school year.

OBJECTIVES

To examine within-child differences in activity and diet behaviours during the summer holidays versus the school year.

METHODS

Children (mean age 9.4 years; 37% male) wore accelerometers (GENEActiv; n = 133), reported activities (Multimedia Activity Recall for Children and Adolescents; n = 133) and parents reported child diet (n = 133) at five timepoints over 2 years capturing school and summer holiday values. Mixed-effects models were used to compare school and summer holiday behaviours.

RESULTS

Children spent less time in moderate- to vigorous-physical activity (-12 min/day; p = 0.001) and sleep (-12 min/day; p < 0.001) and more time sedentary (+27 min/day; p < 0.001) during summer holidays versus the school year. Screentime (+70 min/day; p < 0.001), domestic/social activities (+43 min/day; p = <0.001), self-care (+24 min/day; p < 0.001), passive transport (+22 min/day; p = 0.001) and quiet time (+16 min/day; p = 0.012) were higher during the summer holidays, compensating for less time in school-related activities (-164 min/day; p < 0.001). Diet quality was lower (-4 points; p < 0.001) and children consumed fewer serves of fruit (-0.4 serves; p < 0.001) during the summer holidays versus the school year.

CONCLUSIONS

Children are displaying poorer activity and diet behaviours during the summer holidays, which may contribute to accelerated weight gain over the holiday period.

The concurrent and longitudinal impact of sleep on mind wandering in early adolescents

Mind wandering refers to task-unrelated thoughts that can interfere with ongoing tasks and could be sleep-driven across childhood. The present study investigated the mechanisms of the association between early adolescents' sleep and mind wandering with emotional symptoms and executive function as potential mediators. A total of 257 early adolescents (baseline aged 9-13 years old; 131 boys) completed the questionnaires consisting of the Pittsburgh Sleep Quality Index, mind wandering, depression and anxiety symptoms, and executive function. Cross-sectional and longitudinal data revealed a sequential mediation pathway of emotional symptoms and executive function in the association between sleep and mind wandering. The mediating effect of emotional symptoms in the link between sleep quality and mind wandering was significant among boys but not girls.

Sleep Deprivation and Insomnia in Adolescence: Implications for Mental Health

Sleep changes significantly throughout the human lifespan. Physiological modifications in sleep regulation, in common with many mammals (especially in the circadian rhythms), predispose adolescents to sleep loss until early adulthood. Adolescents are one-sixth of all human beings and are at high risk for mental diseases (particularly mood disorders) and self-injury. This has been attributed to the incredible number of changes occurring in a limited time window that encompasses rapid biological and psychosocial modifications, which predispose teens to at-risk behaviors. Adolescents' sleep patterns have been investigated as a biunivocal cause for potential damaging conditions, in which insufficient sleep may be both a cause and a consequence of mental health problems. The recent COVID-19 pandemic in particular has made a detrimental contribution to many adolescents' mental health and sleep quality. In this review, we aim to summarize the knowledge in the field and to explore implications for adolescents' (and future adults') mental and physical health, as well as to outline potential strategies of prevention.

Six-year trends and intersectional correlates of meeting 24-Hour Movement Guidelines among South Korean adolescents: Korea Youth Risk Behavior Surveys, 2013-2018

BACKGROUND

Grounded in intersectionality theory, this study examined the 6-year prevalence trend and correlates in meeting Canada's 24-Hour Movement Guidelines (Guidelines hereafter) in a nationally representative adolescent samples of South Korea (officially the Republic of Korea).

METHODS

Self-reported, annually repeated cross-sectional data collected between 2013 and 2018 were used (n = 372,433, 12-17 years old, 47.9% females). Adolescents were categorized as meeting or not meeting different sets of physical activity, screen time (ST), and sleep recommendations within the Guidelines, separately for weekdays and weekend days. Intersectional correlates included sex and social class (i.e., family economic status, parental education level, and academic performance). Multiple logistic regression analyses were performed.

RESULTS

Overall, the proportion of adolescents meeting physical activity, ST, and sleep recommendations were 5.3%, 60.3%, and 10.2% on weekdays and 5.3%, 28.2%, and 46.4% on weekend days, respectively. Between 2013 and 2018, no substantial changes were observed for meeting the physical activity or sleep recommendation, while meeting the ST recommendation was markedly lower in 2018. The proportion of meeting all 3 recommendations were 0.5% for weekdays and 0.8% for weekend days. Overall, compared to female adolescents, male adolescents were consistently associated with more favorable patterns of meeting different sets of recommendations, regardless of social class. Among females only, social class appeared to be not important or even detrimental in meeting different sets of recommendations. Being male, compounded with social class, was associated with meeting the ST recommendation.

CONCLUSION

Less than 1% of Korean adolescents met the overall Guidelines. Intersectionality-based analysis and intervention may be important in promoting healthy active lifestyles among South Korean adolescents.

Agreement between actigraphy and sleep diaries: A 28-day real-time monitoring study among suicidal adolescents following acute psychiatric care

OBJECTIVE

To examine the agreement between, and adherence to, wrist actigraphy and digital sleep diaries as methods for sleep assessment among high-risk adolescents in the 28 days following discharge from acute psychiatric care. Sleep parameters included: number of nighttime awakenings (NWAK), sleep efficiency (SE), sleep onset latency (SOL), total sleep time (TST), and wake after sleep onset (WASO).

METHODS

Fifty-three adolescents (12-18 years) were recruited following discharge from acute psychiatric care for suicide risk. Adolescents completed a baseline assessment followed by a 28-day monitoring period with daily sleep diaries and continuous wrist actigraphy. Bland-Altman and multi-level models examined agreement.

RESULTS

Adherence to actigraphy was high, but lower for sleep diaries; a similar pattern of adherence emerged on weekdays vs. weekends. Bland-Altman analyses revealed no clinically meaningful bias for sleep parameters (except NWAK), but the limits of agreement make interpretation ambiguous. Our base model indicated strong agreement between actigraphy and sleep diaries for TST (r = 0.850), moderate for SOL (r = 0.325) and SE (r = 0.322), and weak for WASO (r = -0.049) and NWAK (r = 0.114). A similar pattern emerged with the insomnia severity models with baseline insomnia influencing agreement on all parameters. There were significant weekday-weekend differences for WASO and NWAK, but not for SOL, SE, and TST.

CONCLUSION

Results suggest that it may be beneficial to find a modeling approach to account for the concordant and discordant information and relevant time-level variables.

A developmental perspective on sleep consistency: Preschool age through emerging adulthood

OBJECTIVE/BACKGROUND

Beyond sleep duration, the regularity of sleep patterns (e.g., sleep consistency), including variability in sleep timing (e.g., bedtime, wake time) and duration, is a critical marker of sleep health. Sleep consistency is captured using a variety of methods within the literature (e.g., sleep intraindividual variability, social jetlag), but most of the research focuses on adolescents.

METHODS

Drawing on a developmental perspective, this narrative review highlights how normative changes at the individual (e.g., biological, cognitive, and social) and contextual (e.g., home, school, sociocultural) levels may contribute to inconsistent sleep patterns across development.

RESULTS AND CONCLUSIONS

This review emphasizes how inconsistent sleep may increase across pivotal transitions throughout development (e.g., elimination of naps, puberty, summertime, entering college). Finally, recommendations for measuring sleep consistency and areas to address in future research are discussed.

What time do you plan to sleep tonight? An intense longitudinal study of adolescent daily sleep self-regulation via planning and its associations with sleep opportunity

BACKGROUND

Most adolescents are sleep deprived on school days, yet how they self-regulate their sleep-wake behaviours is poorly understood. Using ecological momentary assessment, this intense longitudinal study explored patterns of adolescents' daily bedtime and risetime planning and execution, and whether these behaviours predicted sleep opportunity.

METHODS

Every afternoon, for 2 school weeks and the subsequent 2 vacation weeks, 205 (54.1% female, 64.4% non-White) adolescents from year 10 to 12 (M ± SD_age  = 16.9 ± 0.9) reported their plans for bedtime (BT) that evening, and for risetimes (RT) the following day. Actual daily sleep was measured via actigraphy and sleep diary.

RESULTS

Some adolescents never planned bedtime (school 19.5%, non-school 53.2%) or risetime (school 1.5%, non-school 24.4%). More adolescents planned consistently (≥75% of days) on school (BT = 29.9%, RT = 61.3%) compared to non-school nights (BT = 3.5%, RT = 2.5%). On average, adolescents went to bed later than planned, with longer delays on non-school (71 min) compared to school nights (46 min). Of those who executed their plans within ≤15 min, more did it consistently (≥75% of days) on school (BT = 40.9%, RT = 67.7%) than on non-school nights/days (BT = 29.7%, RT = 58.6%). Mixed effects models utilizing daily data, controlling for sex, race, and study day, showed that bedtime planning predicted longer time in bed (TIB; p < .01) on school and shorter TIB on non-school nights (p < .01); and greater delay in actual (compared to planned) BT predicted shorter TIB (p < .001).

CONCLUSIONS

Adolescents may require support during the transition from parent-controlled to autonomous sleep self-regulation. Bedtime planning on school nights and going to bed as planned are two modifiable sleep regulatory behaviours that are protective and potential therapeutic targets for increasing sleep opportunity in adolescents.

Sleep's role in the development and resolution of adolescent depression

Two adolescent mental health fields - sleep and depression - have advanced largely in parallel until about four years ago. Although sleep problems have been thought to be a symptom of adolescent depression, emerging evidence suggests that sleep difficulties arise before depression does. In this Review, we describe how the combination of adolescent sleep biology and psychology uniquely predispose adolescents to develop depression. We describe multiple pathways and contributors, including a delayed circadian rhythm, restricted sleep duration and greater opportunity for repetitive negative thinking while waiting for sleep. We match each contributor with evidence-based sleep interventions, including bright light therapy, exogenous melatonin and cognitive-behaviour therapy techniques. Such treatments improve sleep and alleviate depression symptoms, highlighting the utility of sleep treatment for comorbid disorders experienced by adolescents.

The CLASS Study (Circadian Light in Adolescence, Sleep and School): protocol for a prospective, longitudinal cohort to assess sleep, light, circadian timing and academic performance in adolescence

BACKGROUND

During adolescence, sleep and circadian timing shift later, contributing to restricted sleep duration and irregular sleep-wake patterns. The association of these developmental changes in sleep and circadian timing with cognitive functioning, and consequently academic outcomes, has not been examined prospectively. The role of ambient light exposure in these developmental changes is also not well understood. Here, we describe the protocol for the Circadian Light in Adolescence, Sleep and School (CLASS) Study that will use a longitudinal design to examine the associations of sleep-wake timing, circadian timing and light exposure with academic performance and sleepiness during a critical stage of development. We also describe protocol adaptations to enable remote data collection when required during the COVID-19 pandemic.

METHODS

Approximately 220 healthy adolescents aged 12-13 years (school Year 7) will be recruited from the general community in Melbourne, Australia. Participants will be monitored at five 6 monthly time points over 2 years. Sleep and light exposure will be assessed for 2 weeks during the school term, every 6 months, along with self-report questionnaires of daytime sleepiness. Circadian phase will be measured via dim light melatonin onset once each year. Academic performance will be measured via national standardised testing (National Assessment Program-Literacy and Numeracy) and the Wechsler Individual Achievement Test-Australian and New Zealand Standardised Third Edition in school Years 7 and 9. Secondary outcomes, including symptoms of depression, anxiety and sleep disorders, will be measured via questionnaires.

DISCUSSION

The CLASS Study will enable a comprehensive longitudinal assessment of changes in sleep-wake timing, circadian phase, light exposure and academic performance across a key developmental stage in adolescence. Findings may inform policies and intervention strategies for secondary school-aged adolescents.

ETHICS AND DISSEMINATION

Ethical approval was obtained by the Monash University Human Research Ethics Committee and the Victorian Department of Education. Dissemination plans include scientific publications, scientific conferences, via stakeholders including schools and media.

STUDY DATES

Recruitment occurred between October 2019 and September 2021, data collection from 2019 to 2023.

Sleep and Type 1 Diabetes Mellitus Management Among Children, Adolescents, and Emerging Young Adults: A Systematic Review

BACKGROUND

Type 1 diabetes mellitus (T1DM) is one of the most common chronic illnesses among the youth. Emerging evidence has suggested poor sleep as a risk factor for glycemic control. This review aimed to examine the associations between sleep characteristics and diabetes management in children, adolescents, and emerging young adults with T1DM.

METHODS

Following PRISMA guidelines, the authors searched articles in PubMed, Web of Science, and Scopus from 2000 through August 2020. Using inclusion and exclusion criteria, observational studies and clinical trials that examined sleep and diabetes management among individuals with T1DM (up to 25 years old) were selected for review.

RESULTS

Twenty-four articles met the review criteria. Most studies did not report differences in self-report sleep between individuals with and without T1DM. However, several studies using objective sleep measures (actigraph and PSG) suggested shorter sleep duration and worse sleep quality in individuals with T1DM. Higher A1C levels and undesirable T1DM self-care behaviors were associated with short and long sleep duration, poor sleep quality, sleep disturbances, and irregular sleep, particularly among adolescent boys, young men and those from immigrant families. Self-care behaviors mediated the associations between sleep and subsequent A1C levels.

CONCLUSIONS

Too much or too little sleep, poor sleep quality, sleep disturbances and sleep variability are associated with undesirable T1DM management. Although more research is needed, our findings indicate the importance of including sleep education in the plan of care for children, adolescents and emerging young adults with T1DM.

Bidirectional association between light exposure and sleep in adolescents

Sleep behaviour is controlled by both circadian and homeostatic influences. Changes in both factors are related to the delayed sleep timing observed in adolescence, which also generates restrictions in their sleep duration. In addition, the circadian factor explains part of the observed influence of light on sleep duration. We recorded 15 high-school students for 23 days (vacation: 11 days; school term: 12 days) using GENEactive accelerometers. We employed a repeated-measures analysis to explore the day-to-day bidirectional association between mean light exposure and sleep behaviour across a period with extreme variability in social pressures. Sleep onset was more than 30 min earlier and sleep duration almost 20 min longer when previous day light was 10 times more intense. Light intensity had a reduction of more than 20% as sleep ended 1 hr later. Besides, sleep onset and offset were both later during vacation than on school days (almost 2 hr and 4 hr, respectively) and free days (almost 1 hr, respectively). Therefore, sleep duration was almost 2 hr longer on vacation and free days than on school days. On the other hand, light exposure intensity was twice as high during vacation days when adjusted by sleep timing. Insufficient sleep duration is a major problem for adolescents. Although we found that light exposure was associated with longer sleep duration, the influence of school start times was greater and ended up prevailing, which explained the short sleep durations observed on school days.

Sleep and affect in adolescents: Bidirectional daily associations over 28-day ecological momentary assessment

We examined bidirectional, temporal associations between daily sleep and affect under naturally restricted (school) and unrestricted (vacation) sleep opportunities, while incorporating valence (positive/negative) and arousal (high/low) dimensions of affect. Sleep and affect were measured over 2 weeks of school and 2 weeks of vacation in 205 adolescents (54.1% females, M_age  = 16.9 years), providing 5,231 days of data. Total sleep time and sleep efficiency were measured using actigraphy and sleep diary. High- and low-arousal positive and negative affect were self-reported each afternoon. Between- and within-person sleep-affect associations were tested using cross-lagged, multilevel models. Lagged outcome, day of the week, study day and socio-demographics were controlled. Bidirectional associations between self-report sleep and affect were found between-persons: longer self-report total sleep time associated with lower high- and low-arousal negative affect. Higher high-arousal positive affect associated with longer actigraphy total sleep time between-persons, but predicted shorter same-night actigraphy total sleep time within-persons. Results did not differ between school and vacation. Significant within-person random effects demonstrate individual differences in daily sleep-affect associations. Associations differed based on sleep measurement and affect dimensions, highlighting the complex sleep-affect relationship. Strong between-person associations between self-report sleep and affect suggest improving either sleep or mood may benefit the other; alternatively, addressing a common cause may lead to changes in both sleep and affect. Although overall high-arousal positive affect was protective of sleep duration, on a day-to-day basis, higher-than-usual high-arousal positive affect may reduce sleep duration on nights it is experienced. Further research needs to identify causes of individual differences in sleep-affect associations.

Short sleep, insomnia symptoms, and evening chronotype are correlated with poorer mood and quality of life in adolescent transgender males

OBJECTIVE

Poor sleep is common among adolescents and associated with impaired mood and health-related quality of life (HRQOL). Transgender individuals are at increased risk of mood problems hypothesized to be due to minority stress; however, no research has investigated associations between sleep and mood in this population. We aimed to examine sleep, mood, and HRQOL in transgender adolescent males.

DESIGN & SETTING

Transgender males age 13-16 were recruited from a U.S. gender diversity clinic.

MEASUREMENTS

Participants completed one week of home actigraphy monitoring. Questionnaires assessed insomnia symptoms, chronotype, mood, and HRQOL. Pearson correlations between sleep, mood, and HRQOL were examined.

RESULTS

A total of 10 participants completed study measures during the school year. Participants obtained less than the recommended 8-10 hours of sleep per night, and half of participants endorsed insomnia symptoms. Greater insomnia symptoms were correlated with higher anxiety (P = .04) and depression (P = .04) symptoms, and poorer Psychosocial HRQOL (P = .03). Earlier weekday and weekend bed and wake times and earlier weekday sleep midpoint were associated with better Wellbeing HRQOL. No other significant correlations between sleep and mood or HRQOL variables were found.

CONCLUSIONS

Anxiety and depression symptoms were associated with self-reported insomnia symptoms, while HRQOL was associated with both insomnia symptoms and objective sleep timing in this sample of adolescent transgender males. Clinicians should assess both sleep and mood symptoms in this population and future research should evaluate the impact of improved sleep and gender-affirming care on mood and HRQOL for transgender adolescents.

Perceived daily sleep need and sleep debt in adolescents: associations with daily affect over school and vacation periods

STUDY OBJECTIVES

To describe trajectories of perceived daily sleep need and sleep debt, and examine if cumulative perceived sleep debt predicts next-day affect.

METHODS

Daily sleep and affect were measured over 2 school weeks and 2 vacation weeks (N=205, 54.1% females, M±SDage = 16.9±0.87 years). Each day, participants wore actigraphs and self-reported the amount of sleep needed to function well the next day (i.e., perceived sleep need), sleep duration, and high- and low-arousal positive and negative affect (PA, NA). Cumulative perceived sleep debt was calculated as the weighted average of the difference between perceived sleep need and sleep duration over the past 3 days. Cross-lagged, multilevel models were used to test cumulative sleep debt as a predictor of next-day affect. Lagged affect, day of the week, study day, and sociodemographics were controlled.

RESULTS

Perceived sleep need was lower early in the school week, before increasing in the second half of the week. Adolescents accumulated perceived sleep debt across school days and reduced it during weekends. On weekends and vacations, adolescents self-reported meeting their sleep need, sleeping the amount, or more than the amount of sleep they perceived as needing. Higher cumulative actigraphy sleep debt predicted higher next-day high arousal NA; higher cumulative diary sleep debt predicted higher NA (regardless of arousal), and lower low arousal PA the following day.

CONCLUSION

Adolescents experienced sustained, cumulative perceived sleep debt across school days. Weekends and vacations appeared to be opportunities for reducing sleep debt. Trajectories of sleep debt during vacation suggested recovery from school-related sleep restriction. Cumulative sleep debt was related to affect on a daily basis, highlighting the value of this measure for future research and interventions.

The impact of chronotype on circadian rest-activity rhythm and sleep characteristics across the week

Circadian rhythms are maintained by a complex "system of systems" that continuously coordinates biological processes with each other and the environment. Although humans predominantly entrain to solar time, individual persons vary in their precise behavioral timing due to endogenous and exogenous factors. Endogenous differences in the timing of individual circadian rhythms relative to a common environmental cue are known as chronotypes, ranging from earlier than average (Morningness) to later than average (Eveningness). Furthermore, individual behavior is often constrained by social constructs such as the 7-day week, and the "sociogenic" impact our social calendar has on our behavioral rhythms is likely modified by chronotype. Our aim in this study was to identify and characterize differences in sleep and rest-activity rhythms (RAR) between weekends and weekdays and between-chronotypes. Male volunteers (n = 24, mean age = 23.46 y) were actigraphically monitored for 4 weeks to derive objective behavioral measures of sleep and RARs. Chronotype was assessed through self-report on the Morningness-Eveningness Questionnaire. Sleep characteristics were derived using Actiware; daily rest-activity rhythms were modeled using a basic 3-parameter cosinor function. We observed that both Eveningness and Morningness Chronotypes were more active and slept later on the weekends than on weekdays. Significant between-chronotype differences in sleep timing and duration were observed within individual days of the week, especially during transitions between weekends and the workweek. Moreover, chronotypes significantly varied in their weekly rhythms: e.g. Morningness Chronotypes generally shifted their sleep duration, timing and quality across work/rest transitions quicker than Eveningness Chronotypes. Although our results should be interpreted with caution due to the limitations of our cosinor model and a homogenous cohort, they reinforce a growing body of evidence that day of the week, chronotype and their interactions must be accounted for in observational studies of human behavior, especially when circadian rhythms are of interest.

Changes in Physical Activity, Sleep, Mental Health, and Social Media Use During COVID-19 Lockdown Among Adolescent Girls: A Mixed-Methods Study

BACKGROUND

To suppress the transmission of coronavirus, many governments, including that of the island of Ireland, implemented a societal lockdown, which included school closures, limits on social gatherings, and time outdoors. This study aimed to evaluate changes in physical activity (PA), mental health, sleep, and social media use among adolescent girls during lockdown.

METHODS

281 female pupils (12-14 y) taking part in the ongoing Walking In Schools study on the island of Ireland self-reported PA, mental health, sleep, and social media use before (September-October 2019) and during lockdown (May-June 2020), via questionnaires. These were supplemented with open-ended structured interviews conducted with 16 girls during lockdown.

RESULTS

During the period of lockdown and school closures, pupils tried new forms of PA and undertook PA with family, but there was no significant change in self-reported PA. There was a decline in health-related quality of life and motivation for exercise; however, self-efficacy for walking and happiness with appearance increased. There was no change in sleep quality or social media usage.

CONCLUSIONS

Despite the many challenges that schools face as they reopen, there is a need to continue to prioritize PA and motivation for exercise to support health and well-being in adolescent girls.

Bi-directional relations between stress and self-reported and actigraphy-assessed sleep: a daily intensive longitudinal study

STUDY OBJECTIVES

Stress is associated with poor and short sleep, but the temporal order of these variables remains unclear. This study examined the temporal and bi-directional associations between stress and sleep and explored the moderating role of baseline sleep complaints, using daily, intensive longitudinal designs.

METHODS

Participants were 326 young adults (Mage = 23.24 ± 5.46), providing >2,500 nights of sleep altogether. Prospective total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO), and sleep efficiency (SE) were measured using actigraphy and sleep diaries. Perceived stress was reported three times daily between: 11:00-15:00, 15:30-19:30, and 20:00-02:00. Sleep complaints were measured at baseline using the PROMIS sleep disturbance scale. Within- and between-person sleep and stress variables were tested using cross-lagged multilevel models.

RESULTS

Controlling for covariates and lagged outcomes, within-person effects showed that higher evening stress predicted shorter actigraphic and self-reported TST (both p < .01). Conversely, shorter actigraphic and self-reported TST predicted higher next-day stress (both p < .001). Longer self-reported SOL and WASO (both p < .001), as well as lower actigraphic (p < .01) and self-reported SE (p < .001), predicted higher next-day stress. Between-person effects emerged only for self-reported TST predicting stress (p < .01). No significant results were found for the moderating role of baseline sleep complaints.

CONCLUSIONS

Results demonstrated bi-directional relations between stress and sleep quantity, and a consistent direction of worse sleep quantity and continuity predicting higher next-day stress. Results highlighted within-individual daily variation as being more important than between-individual differences when examining sleep and daytime functioning associations.

Influence of Training Schedules on Objective Measures of Sleep in Adolescent Academy Football Players

Brown, GA, Veith, S, Sampson, JA, Whalan, M, and Fullagar, HHK. Influence of training schedules on objective measures of sleep in adolescent academy football players. J Strength Cond Res 34(9): 2515-2521, 2020-Football academy settings may pose risks to adolescent athletes achieving sufficient sleep because of the contextual challenges these players face (e.g., psychosocial pressure, changes in training, competition, and academic stress). Given the importance of sleep to overall health as well as physical athletic development and injury risk, this study aimed to investigate whether differences in training schedules (morning vs. evening training sessions) affected objective measures of sleep in adolescent academy football (soccer) players. Twelve academy players (mean age 14.18 ± 1.36 years) wore an ActiGraph accelerometer on nights before, and nights of, training days in 2 separate weeks where morning (09:00-11:00 hours) and evening (18:00-20:00 hours) training occurred. Objective sleep parameters and training load data were collected. Night-time sleep periods were categorized as sleep preceding morning training, preceding evening training, or after evening training. One-way univariate and multivariate analyses of variance for repeated measures were performed to determine the impact of the training schedule on sleep. Significance levels were set at p < 0.05. The total sleep time was below the recommended guidelines (<8 hours) across conditions. A large significant effect of the training schedule on time attempted to fall asleep (p = 0.004, effect size [ES] = 0.40) and time of sleep (p = 0.003, ES = 0.41) was present, with post-evening sessions resulting in the latest times. Overall, the players' sleep behavior was resilient to changes in training schedules. However, the low sleep durations (and potential risks to physical performance/injury) suggest that sleep education coupled with practical interventions are required in this cohort.

Sleep in Myopic and Non-Myopic Children

Purpose

To examine differences in sleep between myopic and non-myopic children.

Methods

Objective measurements of sleep, light exposure, and physical activity were collected from 91 children, aged 10 to 15 years, for two 14-day periods approximately 6 months apart. Sleep parameters were analyzed with respect to refractive error, season, day of the week, age, and sex.

Results

Myopic children exhibited differences in sleep duration by day of the week (P < 0.001) and season (P = 0.007). Additionally, myopic children exhibited shorter sleep latency than non-myopic children (P = 0.04). For all children, wake time was later (P < 0.001) and sleep duration was longer (P = 0.03) during the cooler season compared with the warmer season. On weekends, children went to bed later (P < 0.001), woke up later (P < 0.001), and had increased sleep duration (P < 0.001) than on weekdays. Younger children exhibited earlier bedtime (P = 0.005) and wake time (P = 0.01) than older children. Time spent outdoors was positively associated with sleep duration (P = 0.03), and daily physical activity was negatively associated with wake time (P < 0.001).

Conclusions

Myopic children tended to have more variable sleep duration and shorter latency than non-myopic children. Sleep patterns were influenced by season, day of the week, age, time outdoors, and activity.

Translational Relevance

Myopic children tended to have more variable sleep duration and shorter latency than non-myopic children, which may reflect previously reported differences in environmental and behavioral factors between refractive error groups.

Short Sleep Duration and Extremely Delayed Chronotypes in Uruguayan Youth: The Role of School Start Times and Social Constraints

During adolescence, biological, psychosocial, and contextual factors converge in a “perfect storm” and have been put forward to explain the delay in chronotype observed at this age and the prevalence of disrupted sleep. This study provides evidence to support that chronotype and sleep patterns (particularly sleep duration) are socially constrained and to identify novel significant social predictors. Uruguayan public school activities are arranged in up to 4 shifts, creating a natural experiment to examine the effect of school timing on questionnaire-based assessments of sleep and chronotype. In this study, 268 high school students (15-18 years old) who attended school either on morning (0730 to 1130 h) or afternoon shifts (1130 h to 1530 h) responded to an adapted School Sleep Habits Survey. Students attending afternoon shifts had later chronotypes (a 1.5-h later midpoint of sleep on free days adjusted for sleep debt) than those attending the morning shift. Besides shift, evening social activities (including dinner time) were further identified as key predictors of late chronotypes, whereas age and gender were not. Sleep on school days was overall advanced and reduced with respect to weekends, and these effects were stronger in morning-shift students. Weekend sleep duration was similar between shifts, which probably caused the prevalence of reduced sleep durations (average weekly sleep duration, SDweek <8 h) to be higher in morning-shift students (almost 80%) than in afternoon-shift ones (34%). Reduced sleep duration was significantly higher in morning-shift students. In addition, age, chronotype, and dinner time became relevant determinants of sleep deficit only in the morning-shift students. Besides the important social constraint of early school start time, this is the first study to confirm the significance of other types of social pressures on both adolescents’ chronotype and sleep deficit, which can be useful as potential new targets for effective policies to protect adolescent sleep.

Measures of circadian preference in childhood and adolescence: A review

Purpose

To review the psychometric properties of the questionnaires commonly filled in by children and adolescents to measure circadian preference.

Methods

We examined the Morningness-Eveningness Questionnaire for Children and Adolescents (MEQ-CA), the Morningness-Eveningness Scale for Children (MESC) and the Composite Scale of Morningness (CSM). We critically analyzed the reliability, in term of internal consistency (through the Cronbach's alpha) and test-retest reliability (through the correlation coefficient), and the type of validation against external criteria (objective assessment of the sleep/wake cycle, body temperature, hormones and other questionnaires). Fifty studies that reported these data were included in the review: 7 studies used the MEQ-CA, 28 used the MESC and 15 used the CSM.

Results

The percentage of studies reporting at least acceptable levels of internal consistency was high and similar between the three questionnaires. Evidence for test-retest reliability was scant, since only 3 studies were available; it was at least acceptable for the MESC (two studies with a time interval of 1 month), not acceptable for the MEQ-CA (one study with a time interval of 6 months), while no information was available for the CSM. As regards the validation evidence, the MEQ-CA has been validated by the highest number of external criteria (actigraphy, oral body temperature and other questionnaires), followed by the CSM (cortisol sampling and other questionnaires). The MESC has been validated only against self-report measures.

Conclusions

The present state of the art would suggest the use of the MEQ-CA to assess circadian preference in children and adolescents.

Sleep Timing During Adolescence: A Latent Transition Analysis Approach

Objective/Background: This paper utilized a person-centered approach to examine individual differences in sleep timing cross-sectionally and prospectively in adolescents. Participants: Data from Waves 5 and 6 of the Longitudinal Study of Australian Children were used. At Wave 5, the sample included 3,552 Australian adolescents aged 12-13 years (51% males, 49% females); 84% provided data at two-year follow-up (Wave 6). Methods: Through structured interviews, adolescents provided information on sleep timing (bedtimes, sleep-onset times, and wake times) on weekends and weekdays, and relevant covariates. Latent profile analysis identified sleep profiles at Waves 5 and 6 separately; latent transition analysis examined stability and change in profiles across time. Results: Six sleep timing profiles were identified at age 12-13 years: Early Larks (n = 228; 6.4%); Larks (n = 1257; 35.4%); Intermediate (n = 1311; 36.9%); Owls (n = 351; 9.9%); Variable Owls (n = 308; 8.7%); and, Late Owls (n = 97; 2.7%). Six similar profiles were identified at age 14-15 years. The latent transition analysis indicated that the Early Larks, Larks, and Intermediate profiles were more stable over time compared with the Owls, Variable Owls, and Late Owls profiles. Higher body mass index (BMI) and longer screen time predicted transitions from Larks and Early Larks to the Owls, Variable Owls, and Late Owls profiles. Conclusions: Many adolescents showed healthy sleep timing, which continued with age. However, the Variable Owls, Owls, and Late Owls profiles reflected less healthy and more variable sleep patterns that may require targeted interventions.

Longitudinal Change in Adolescent Bedtimes Measured by Self-Report and Actigraphy

Introduction:

Sleep is often quantified using self-report or actigraphy. Self-report is practical and less technically challenging, but prone to bias. We sought to determine whether these methods have comparable sensitivity to measure longitudinal changes in adolescent bedtimes.

Methods:

We measured one week of free-living sleep with wrist actigraphy and usual bedtime on school nights and non-school nights with self-report questionnaire in 144 students at 15 y and 17 y.

Results:

Self-reported and actigraphy-measured bedtimes were correlated with one another at 15 y and 17 y (p < .001), but reported bedtime was consistently earlier (>30 minutes, p < .001) and with wide inter-method confidence intervals (> ±106 minutes). Mean inter-method discrepancy did not differ on school nights at 15 y and 17 y but was greater at 17 y on non-school nights (p = .002). Inter-method discrepancy at 15 y was not correlated to that at 17 y. Mean change in self-reported school night bedtime from 15 y to 17 y did not differ from that by actigraphy, but self-reported bedtime changed less on non-school nights (p = .002). Two-year changes in self-reported bedtime did not correlate with changes measured by actigraphy.

Conclusions:

Although methods were correlated, consistently earlier self-reported bedtime suggests report-bias. More varied non-school night bedtimes challenge the accuracy of self-report and actigraphy, reducing sensitivity to change. On school nights, the methods did not differ in group-level sensitivity to changes in bedtime. However, lack of correlation between bedtime changes by each method suggests sensitivity to individual-level change was different. Methodological differences in sensitivity to individual- and group-level change should be considered in longitudinal studies of adolescent sleep patterns.

Sleep and stress in adolescents: the roles of pre-sleep arousal and coping during school and vacation

STUDY OBJECTIVES

This study explored the relationship between stress and actigraphy-measured and self-reported sleep in adolescents during periods of restricted (school) and unrestricted (vacation) sleep opportunities. We further examined whether (1) cognitive pre-sleep arousal (PSA) mediated the relationship between stress and sleep onset latency (SOL), and (2) coping moderated the effect of stress on PSA.

METHODS

Participants were 146 (77 females) adolescents (M = 16.2, SD = 1.0) recruited from the community. Actigraphy assessed daily sleep over the last week of a school-term and the following two-week vacation. The following self-report measures were administered during both school and vacation: the Pittsburgh Sleep Quality Index, Inventory of High-School Students Recent Life Experiences (stress), Pre-Sleep Arousal Scale, and the Brief COPE (coping).

RESULTS

Path analyses showed that during both school and vacation, higher cognitive PSA mediated the relationship between higher stress and longer self-report SOL (p < 0.01). During vacation, higher PSA also mediated the relationship between higher stress and longer actigraphy SOL (p < 0.05). During vacation (but not school), problem-focused coping moderated the mediating effects of PSA (p < 0.05), such that more frequent use of coping was associated with weaker association between stress and cognitive PSA, and shorter actigraphy and self-report SOL.

CONCLUSIONS

Cognitive PSA and coping may be two modifiable factors influencing how stress affects adolescents' sleep onset. Interventions that reduce cognitive arousal at bedtime may therefore shorten adolescents' sleep onset during both school and vacation. Further, the use of problem-focused coping strategies might be protective against the effects of stress on sleep onset, especially during vacation periods.

STATEMENT OF SIGNIFICANCE

This paper expands the understanding of the stress-sleep association in adolescents by examining the mediating role of cognitive pre-sleep arousal and the moderating effects of coping. By examining these associations during both school and vacation periods, findings are likely to be applicable to both restricted and relatively unconstrained sleep conditions. Practically, our findings suggest that interventions directed towards the reduction of cognitive pre-sleep arousal may improve adolescents' sleep onset latency. Additionally, fostering healthy coping, especially problem-focused coping strategies such as problem solving, may mitigate the effects of stress on adolescents' sleep.

Objective sleep outcomes 20 years after traumatic brain injury in childhood

Purpose: To assess objective sleep outcomes and correlates in young adults with a history of childhood traumatic brain injury.Materials and methods: Participants included 45 young adults who sustained brain injury in childhood (mild = 12, moderate = 22, and severe = 11) and 13 typically developing control participants. Sleep was assessed with actigraphy and sleep diaries recorded over 14 consecutive days. Rates of good sleep (sleep efficiency ≥ 85%) and poor sleep (sleep efficiency < 85%) were also evaluated.Results: At 20-years postinjury, participants with traumatic brain injury and controls presented with similar outcomes across the objective sleep parameters (all p > 0.050) and rates of poor sleepers were also similar between these groups (p = 0.735): 67% and 77%, respectively. However, moderate and severe traumatic brain injury and female sex were associated with longer sleep duration.Conclusions: These findings provide preliminary insights into objective sleep outcome and associated factors in the very-long-term after childhood brain injuries. They also indicate the need to monitor sleep outcomes in young adults with and without traumatic brain injury.Implication for rehabilitationSustaining traumatic brain injury in childhood can impact on several functional domains including sleep.Sleep disturbances, particularly insomnia-related symptoms, are common in this population, with evidence of poor outcomes reported until adolescence postinjury, while outcomes beyond adolescence remain unexplored.In this first investigation of objective sleep outcomes in young adults with a history of childhood traumatic brain injury, we showed that insomnia-related symptoms are highly prevalent in both young adults with traumatic brain injury (67%) and healthy controls (77%).These findings suggest the need to routinely evaluate and treat sleep problem in young adults in general, irrespective of history of childhood traumatic brain injury.

Changes in children's sleep and physical activity during a 1-week versus a 3-week break from school: a natural experiment

Study Objectives

To examine changes in elementary aged children's sleep and physical activity during a 1-week and a 3-week school break.

Methods

Sleep and physical activity of elementary children (n = 154, age = 5-9 years, 44.8% female, 65.5% African American) were collected over 7 weeks that included a 1-week break in two schools and a 3-week break in a single school. Mixed regression models estimated sleep and physical activity changes within and between groups (i.e. 1-week vs. 3-weeks) during school and school break weeks.

Results

Compared to school weeks, bed times shifted 72.7 (95% CI = 57.5, 87.9) and 75.4 (95% CI = 58.1, 92.7) minutes later on weekdays during the 1-week and 3-week break, respectively. Wake times shifted 111.6 (95% CI = 94.3, 128.9) and 99.8 (95% CI = 80.5, 119.1) minutes later on weekdays during 1-week and 3-week breaks. On weekdays during the 3-week break, children engaged in 33.1 (95% CI = 14.1, 52.2) more sedentary minutes and -12.2 (-20.2, -4.2) fewer moderate-to-vigorous physical activity minutes/day. No statistically significant changes in children's sedentary, light, or moderate-to-vigorous physical activity (MVPA) minutes were observed on weekdays during the 1-week break. Between-group differences in the change in time sedentary (32.1-95% CI = 5.8, 58.4), and moderate-to-vigorous (-13.0-95% CI = -23.9, -2.0) physical activity were observed.

Conclusions

Children's sleep shifted later on both 1-week and 3-week breaks. Children's activity changed minimally on weekdays during a 1-week school break and more during a 3-week school break. Displaced sleep and reductions in activity are intervention targets for mitigating unhealthy weight gain during extended breaks from school.

Sleep Physiology, Circadian Rhythms, Waking Performance and the Development of Sleep-Wake Therapeutics

Disturbances of the sleep-wake cycle are highly prevalent and diverse. The aetiology of some sleep disorders, such as circadian rhythm sleep-wake disorders, is understood at the conceptual level of the circadian and homeostatic regulation of sleep and in part at a mechanistic level. Other disorders such as insomnia are more difficult to relate to sleep regulatory mechanisms or sleep physiology. To further our understanding of sleep-wake disorders and the potential of novel therapeutics, we discuss recent findings on the neurobiology of sleep regulation and circadian rhythmicity and its relation with the subjective experience of sleep and the quality of wakefulness. Sleep continuity and to some extent REM sleep emerge as determinants of subjective sleep quality and waking performance. The effects of insufficient sleep primarily concern subjective and objective sleepiness as well as vigilant attention, whereas performance on higher cognitive functions appears to be better preserved albeit at the cost of increased effort. We discuss age-related, sex and other trait-like differences in sleep physiology and sleep need and compare the effects of existing pharmacological and non-pharmacological sleep- and wake-promoting treatments. Successful non-pharmacological approaches such as sleep restriction for insomnia and light and melatonin treatment for circadian rhythm sleep disorders target processes such as sleep homeostasis or circadian rhythmicity. Most pharmacological treatments of sleep disorders target specific signalling pathways with no well-established role in either sleep homeostasis or circadian rhythmicity. Pharmacological sleep therapeutics induce changes in sleep structure and the sleep EEG which are specific to the mechanism of action of the drug. Sleep- and wake-promoting therapeutics often induce residual effects on waking performance and sleep, respectively. The need for novel therapeutic approaches continues not at least because of the societal demand to sleep and be awake out of synchrony with the natural light-dark cycle, the high prevalence of sleep-wake disturbances in mental health disorders and in neurodegeneration. Novel approaches, which will provide a more comprehensive description of sleep and allow for large-scale sleep and circadian physiology studies in the home environment, hold promise for continued improvement of therapeutics for disturbances of sleep, circadian rhythms and waking performance.

Modifying the Impact of Eveningness Chronotype ("Night-Owls") in Youth: A Randomized Controlled Trial

OBJECTIVE

To determine whether an intervention to reduce eveningness chronotype improves sleep, circadian, and health (emotional, cognitive, behavioral, social, physical) outcomes.

METHOD

Youth aged 10 to 18 years with an evening chronotype and who were "at risk" in 1 of 5 health domains were randomized to: (a) Transdiagnostic Sleep and Circadian Intervention for Youth (TranS-C; n = 89) or (b) Psychoeducation (PE; n = 87) at a university-based clinic. Treatments were 6 individual, weekly 50-minute sessions during the school year. TranS-C addresses sleep and circadian problems experienced by youth by integrating evidence-based treatments derived from basic research. PE provides education on the interrelationship between sleep, stress, diet, and health.

RESULTS

Relative to PE, TranS-C was not associated with greater pre-post change for total sleep time (TST) or bed time (BT) on weeknights but was associated with greater reduction in evening circadian preference (pre-post increase of 3.89 points, 95% CI = 2.94-4.85, for TranS-C, and 2.01 points, 95% CI = 1.05-2.97 for PE, p = 0.006), earlier endogenous circadian phase, less weeknight-weekend discrepancy in TST and wakeup time, less daytime sleepiness, and better self-reported sleep via youth and parent report. In terms of functioning in the five health domains, relative to PE, TranS-C was not associated with greater pre-post change on the primary outcome. However, there were significant interactions favoring TranS-C on the Parent-Reported Composite Risk Scores for cognitive health.

CONCLUSION

For at-risk youth, the evidence supports the use of TranS-C over PE for improving sleep and circadian functioning, and improving health on selected outcomes.

CLINICAL TRIAL REGISTRATION INFORMATION

Triple Vulnerability? Circadian Tendency, Sleep Deprivation and Adolescence. https://clinicaltrials.gov; NCT01828320.

Positive and Negative Emotions: Differential Associations with Sleep Duration and Quality in Adolescents

Despite positive and negative emotions being equally important predictors of adolescent wellbeing, research examining positive emotions is limited. In 4582 adolescents (69.4% females; age M ± SD = 14.55 ± 1.74 years), we used structural equation modelling to examine associations between self-reported sleep duration and quality with positive affect, negative affect, and happiness, controlling for age and sex. Overall, sleep quality displayed stronger associations with all measures of emotions compared to sleep duration. Shorter sleep was more specifically associated with lower positive emotions (happiness, followed by positive affect), whereas poorer sleep showed stronger associations with negative affect. Protecting sleep duration may promote positive emotions and enhancing sleep quality may reduce mood disturbances. Future research could incorporate both positive and negative emotions to better understand adolescents' wellbeing.

Insomnia disorder in adolescence: Diagnosis, impact, and treatment

Insomnia disorder is very common in adolescents; it is particularly manifest in older adolescents and girls, with a prevalence comparable to that of other major psychiatric disorders (e.g., depressive disorders). However, insomnia disorder in adolescence is poorly characterized, under-recognized, under-diagnosed, and under-treated, and the reason for the female preponderance for insomnia that emerges after puberty is largely unknown. Insomnia disorder goes beyond an individual complaint of poor sleep or a sleep state misperception, and there is emerging evidence supporting the association of insomnia symptoms in adolescents with alterations in several bio-systems including functional cortical alterations and systemic inflammation. Insomnia disorder is associated with depression and other psychiatric disorders, and is an independent risk factor for suicidality and substance use in adolescents, raising the possibility that treating insomnia symptoms in early adolescence may reduce risk for these adverse outcomes. Cognitive behavioral treatments have proven efficacy for adolescent insomnia and online methods seem to offer promising cost-effective options. Current evidence indicates that insomnia in adolescence is an independent entity that warrants attention as a public health concern in its own right.