Cognitive Performance, Sleepiness, and Mood in Partially Sleep Deprived Adolescents: The Need for Sleep Study

Alcohol use severity and the neural correlates of the effects of sleep disturbance on sustained visual attention

Alcohol misuse is associated with sleep disturbance and cognitive dysfunction. However, the neural processes inter-relating the severity of alcohol use, sleep disturbance and cognitive performance remain under-investigated. We addressed this issue with a dataset of 964 subjects (504 women) curated from the Human Connectome Project. Participants were assessed with the Pittsburgh Sleep Quality Index (PSQI) and fMRI while identifying relational dimension pictures and matching dimension pictures (as a control) in alternating blocks. Imaging data were analyzed with published routines and the results were evaluated at a corrected threshold. Subjects showed lower accuracy rate and longer reaction time (RT) in relational than control blocks. The difference in RT between the two blocks (RT_Rel-Con) was driven primarily by the RT and correlated positively with performance accuracy of relational trials, suggesting that a more cautious response (i.e., longer RT_Rel-Con) improved accuracy. The severity of alcohol use, identified from principal component analysis of drinking metrics, was positively correlated with sleep disturbance. Further, whole-brain regression identified activity of the superior colliculus (SC) during relational vs. control blocks in positive and negative correlation with RT_Rel-Con and PSQI score, respectively. Mediation and path analyses demonstrated a significant model: more severe alcohol use → greater sleep disturbance → diminished SC activity → impaired performance. These findings support the influences of alcohol misuse on sleep and suggest neural correlates that mediate the relationship between sleep disturbance and altered sustained attention in young adults.

Circadian Synchrony: Sleep, Nutrition, and Physical Activity

The circadian clock in mammals regulates the sleep/wake cycle and many associated behavioral and physiological processes. The cellular clock mechanism involves a transcriptional negative feedback loop that gives rise to circadian rhythms in gene expression with an approximately 24-h periodicity. To maintain system robustness, clocks throughout the body must be synchronized and their functions coordinated. In mammals, the master clock is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN is entrained to the light/dark cycle through photic signal transduction and subsequent induction of core clock gene expression. The SCN in turn relays the time-of-day information to clocks in peripheral tissues. While the SCN is highly responsive to photic cues, peripheral clocks are more sensitive to non-photic resetting cues such as nutrients, body temperature, and neuroendocrine hormones. For example, feeding/fasting and physical activity can entrain peripheral clocks through signaling pathways and subsequent regulation of core clock genes and proteins. As such, timing of food intake and physical activity matters. In an ideal world, the sleep/wake and feeding/fasting cycles are synchronized to the light/dark cycle. However, asynchronous environmental cues, such as those experienced by shift workers and frequent travelers, often lead to misalignment between the master and peripheral clocks. Emerging evidence suggests that the resulting circadian disruption is associated with various diseases and chronic conditions that cause further circadian desynchrony and accelerate disease progression. In this review, we discuss how sleep, nutrition, and physical activity synchronize circadian clocks and how chronomedicine may offer novel strategies for disease intervention.

Interindividual differences in attentional vulnerability moderate cognitive performance during sleep restriction and subsequent recovery in healthy young men

We investigated whether interindividual attentional vulnerability moderates performance on domain-specific cognitive tasks during sleep restriction (SR) and subsequent recovery sleep. Fifteen healthy men (M ± SD, 22.3 ± 2.8 years) were exposed to three nights of baseline, five nights of 5-h time in bed SR, and two nights of recovery sleep. Participants completed tasks assessing working memory, visuospatial processing, and processing speed approximately every two hours during wake. Analyses examined performance across SR and recovery (linear predictor day or quadratic predictor day²) moderated by attentional vulnerability per participant (difference between mean psychomotor vigilance task lapses after the fifth SR night versus the last baseline night). For significant interactions between day/day² and vulnerability, we investigated the effect of day/day² at 1 SD below (less vulnerable level) and above (more vulnerable level) the mean of attentional vulnerability (N = 15 in all analyses). Working memory accuracy and speed on the Fractal 2-Back and visuospatial processing speed and efficiency on the Line Orientation Task improved across the entire study at the less vulnerable level (mean − 1SD) but not the more vulnerable level (mean + 1SD). Therefore, vulnerability to attentional lapses after SR is a marker of susceptibility to working memory and visuospatial processing impairment during SR and subsequent recovery.

Metabolic Disturbances Induced by Sleep Restriction as Potential Triggers for Alzheimer's Disease

Sleep has a major role in learning, memory consolidation, and metabolic function. Although it is known that sleep restriction increases the accumulation of amyloid β peptide (Aβ) and the risk to develop Alzheimer's disease (AD), the mechanism behind these effects remains unknown. In this review, we discuss how chronic sleep restriction induces metabolic and cognitive impairments that could result in the development of AD in late life. Here, we integrate evidence regarding mechanisms whereby metabolic signaling becomes disturbed after short or chronic sleep restriction in the context of cognitive impairment, particularly in the accumulation of Aβ in the brain. We also discuss the role of the blood-brain barrier in sleep restriction with an emphasis on the transport of metabolic signals into the brain and Aβ clearance. This review presents the unexplored possibility that the alteration of peripheral metabolic signals induced by sleep restriction, especially insulin resistance, is responsible for cognitive deficit and, subsequently, implicated in AD development.

Altered Functional Connectivity in the Resting State Neostriatum After Complete Sleep Deprivation: Impairment of Motor Control and Regulatory Network

Sleep loss not only compromises individual physiological functions but also induces a psychocognitive decline and even impairs the motor control and regulatory network. In this study, we analyzed whole-brain functional connectivity changes in the putamen and caudate nucleus as seed points in the neostriatum after 36 h of complete sleep deprivation in 30 healthy adult men by resting state functional magnetic resonance imaging to investigate the physiological mechanisms involved in impaired motor control and regulatory network in individuals in the sleep-deprived state. The functional connectivity between the putamen and the bilateral precentral, postcentral, superior temporal, and middle temporal gyrus, and the left caudate nucleus and the postcentral and inferior temporal gyrus were significantly reduced after 36 h of total sleep deprivation. This may contribute to impaired motor perception, fine motor control, and speech motor control in individuals. It may also provide some evidence for neurophysiological changes in the brain in the sleep-deprived state and shed new light on the study of the neostriatum in the basal ganglia.

In-person vs home schooling during the COVID-19 pandemic: Differences in sleep, circadian timing, and mood in early adolescence

During the COVID-19 pandemic, schools around the world rapidly transitioned from in-person to remote learning, providing an opportunity to examine the impact of in-person vs remote learning on sleep, circadian timing, and mood. We assessed sleep-wake timing using wrist actigraphy and sleep diaries over 1-2 weeks during in-person learning (n = 28) and remote learning (n = 58, where n = 27 were repeat assessments) in adolescents (age M ± SD = 12.79 ± 0.42 years). Circadian timing was measured under a single condition in each individual using salivary melatonin (Dim Light Melatonin Onset; DLMO). Online surveys assessed mood (PROMIS Pediatric Anxiety and Depressive Symptoms) and sleepiness (Epworth Sleepiness Scale - Child and Adolescent) in each condition. During remote (vs in-person) learning: (i) on school days, students went to sleep 26 minutes later and woke 49 minutes later, resulting in 22 minutes longer sleep duration (all P < .0001); (ii) DLMO time did not differ significantly between conditions, although participants woke at a later circadian phase (43 minutes, P = .03) during remote learning; and (iii) participants reported significantly lower sleepiness (P = .048) and lower anxiety symptoms (P = .006). Depressive symptoms did not differ between conditions. Changes in mood symptoms were not mediated by sleep. Although remote learning continued to have fixed school start times, removing morning commutes likely enabled adolescents to sleep longer, wake later, and to wake at a later circadian phase. These results indicate that remote learning, or later school start times, may extend sleep and improve some subjective symptoms in adolescents.

Cortical Thinning and Sleep Slow Wave Activity Reductions Mediate Age-Related Improvements in Cognition During Mid-Late Adolescence

Study Objectives

Gains in cognitive test performance that occur during adolescence are associated with brain maturation. Cortical thinning and reduced sleep slow wave activity (SWA) are markers of such developmental changes. Here we investigate whether they mediate age-related improvements in cognition.

Methods

109 adolescents aged 15–19 years (49 males) underwent magnetic resonance imaging, polysomnography (PSG), and a battery of cognitive tasks within a 2-month time window. Cognitive tasks assessed nonverbal intelligence, sustained attention, speed of processing and working memory and executive function. To minimize the effect of sleep history on SWA and cognitive performance, PSG and test batteries were administered only after at least 8 nights of 9-h time-in-bed (TIB) sleep opportunity.

Results

Age-related improvements in speed of processing (r = 0.33, p = 0.001) and nonverbal intelligence (r = 0.24, p = 0.01) domains were observed. These cognitive changes were associated with reduced cortical thickness, particularly in bilateral temporoparietal regions (rs = −0.21 to −0.45, ps < 0.05), as well as SWA (r = −0.35, p < 0.001). Serial mediation models found that ROIs in the middle/superior temporal cortices, together with SWA mediated the age-related improvement observed on cognition.

Conclusions

During adolescence, age-related improvements in cognition are mediated by reductions in cortical thickness and sleep SWA.

Obstructive Sleep Apnea: Cognitive Outcomes

There is a strong association between obstructive sleep apnea (OSA) and cognitive dysfunction. Executive function, attention, verbal/visual long-term memory, visuospatial/constructional ability, and information processing are more likely to be affected, whereas language, psychomotor function, and short-term memory are less likely to be affected. Increased accumulation of Aß₂-amyloid in the brain, episodic hypoxemia, oxidative stress, vascular inflammation, and systemic comorbidities may contribute to the pathogenesis. Patients with OSA should have cognitive screening or formal testing, and patients with cognitive decline should have testing for OSA. Treatment with continuous positive airway pressure may improve cognitive symptoms in the patient with OSA.

It's not all about the likes: Social media affordances with nighttime, problematic, and adverse use as predictors of adolescent sleep indicators

OBJECTIVES

Adolescents are the most prominent users of social media, and their exposure to different contents, platforms, and types of use continues to develop. At the same time, sleep deprivation is on the rise, which may contribute to worsened health. Therefore, this cross-sectional study set out to examine the relationships among several social media affordances, habits of use, and sleep indicators in adolescents.

METHODS

Students ages 12-18 from a high school on Long Island, New York (N = 410) participated in an anonymous online survey focusing on various aspects of social media use as well as major sleep indicators (sleep displacement, presleep arousal, sleep quality, fatigue).

RESULTS

Snapchat was the only platform to predict a worsened sleep indicator (later bedtime) and it correlated with problematic, adverse, and nighttime use, possibly due to closer relationships among users. More viewing of posts of sports, friends, and family predicted better sleep. Additionally, nighttime social media use, problematic social media use, and adverse social media use each predicted at least one worsened sleep indicator in a hierarchical regression model.

CONCLUSIONS

Although some implications were positive, results provided insight into the cons of social media use. This study provides evidence that in order to understand the role of social media in the sleep-wake process, one must look at the specific affordances each platform provides and the different nighttime, problematic, and adverse habits of use that can arise. Documenting the variety of media use behaviors, however, introduces a considerable multiple testing threat to this research area.

Daytime sleepiness underlies the link between adverse parenting and youth psychopathology among adolescent girls

INTRODUCTION

Adverse parenting is associated with sleep problems in adolescence, including sleep quality, inadequate sleep, and daytime sleepiness. Adolescents who experience sleep problems are at greater risk for developing internalizing and externalizing problems. However, research on the intervening role of sleep in the link between adverse parenting and youth psychopathology remains limited. The present study aimed to examine the indirect effects of adverse parenting on youth internalizing and externalizing psychopathology via sleep problems, and to examine the moderating role of gender in associations between parenting and sleep.

METHODS

Participants were 101 low-income youth aged 9-12 (52.5% female; 75.2% African-American) and their primary caregivers. Families were from a non-metropolitan region in the Southeastern United States. Data were collected at two time points (T1; Mage = 10.28, SD = 1.2; T2; Mage = 12.08, SD = 1.2). Adverse parenting was measured at T1, youth-reported sleep problems (inadequacy, disturbance) and daytime sleepiness were assessed at T2, and parent-reported internalizing and externalizing symptoms were measured at T2.

RESULTS

Daytime sleepiness served as an intervening variable in associations between adverse parenting and internalizing and externalizing problems, but sleep problems did not. This indirect association was moderated by gender, such that the association between adverse parenting and daytime sleepiness only emerged as significant for girls.

CONCLUSIONS

These findings suggest that daytime-related sleep behaviors may serve as a mechanism through which harsh or neglectful parenting is related to internalizing and externalizing psychopathology in adolescence, particularly for adolescent girls.

Effects of sleep restriction on the sleep electroencephalogram of adolescents

STUDY OBJECTIVES

This report describes findings from an ongoing longitudinal study of the effects of varied sleep durations on wake and sleep electroencephalogram (EEG) and daytime function in adolescents. Here, we focus on the effects of age and time in bed (TIB) on total sleep time (TST) and nonrapid eye movement (NREM) and rapid eye movement (REM) EEG.

METHODS

We studied 77 participants (41 male) ranging in age from 9.9 to 16.2 years over the 3 years of this study. Each year, participants adhered to each of three different sleep schedules: four consecutive nights of 7, 8.5, or 10 h TIB.

RESULTS

Altering TIB successfully modified TST, which averaged 406, 472 and 530 min on the fourth night of 7, 8.5, and 10 h TIB, respectively. As predicted by homeostatic models, shorter sleep durations produced higher delta power in both NREM and REM although these effects were small. Restricted sleep more substantially reduced alpha power in both NREM and REM sleep. In NREM but not REM sleep, sleep restriction strongly reduced both the all-night accumulation of sigma EEG activity (11-15 Hz energy) and the rate of sigma production (11-15 Hz power).

CONCLUSIONS

The EEG changes in response to TIB reduction are evidence of insufficient sleep recovery. The decrease in sigma activity presumably reflects depressed sleep spindle activity and suggests a manner by which sleep restriction reduces waking cognitive function in adolescents. Our results thus far demonstrate that relatively modest TIB manipulations provide a useful tool for investigating adolescent sleep biology.

Sleep timing and consistency are associated with the standardised test performance of Icelandic adolescents

Sleep has been shown to affect cognitive function in laboratory studies; however, its association to the academic performance of adolescents has largely been demonstrated using self-reported measures. Studies with objective measures of both sleep and academic performance are limited. The aim of the present study was to determine whether the free-living sleep quantity, quality, and timing of 15-year-old adolescents measured with wrist actiography are associated with their scores on national standardised examinations as an objective measure of academic achievement. We measured sleep with wrist actiography for 1 week in 253 (150 girls) Icelandic adolescents with a mean (SD) age of 15.9 (0.3) years. Multiple linear regression was used to assess associations between sleep parameters and combined standardised examination scores in mathematics, English, and Icelandic obtained from the Icelandic Directorate of Education. We found that students went to bed at 00:49 hours (± 51.8 min) and slept for a mean (SD) of 6.6 (0.7) hr/night, with a median (interquartile range) night-to-night variation in sleep duration of 1.2 (0.7) hr and an efficiency of 88.1 (5.3)%. Combined analyses adjusted for sex, demonstrated that both bedtime and night-to-night variability in total sleep time were negatively associated with the average score across all topics. Sex-specific associations did not indicate clear differences between boys and girls. These findings suggest that, in addition to appropriate sleep duration, public health guidance should also highlight the importance of early and consistent sleep schedules to academic achievement for both boys and girls.

The effect of sleep deprivation and restriction on mood, emotion, and emotion regulation: three meta-analyses in one

STUDY OBJECTIVES

New theory and measurement approaches have facilitated nuanced investigation of how sleep loss impacts dimensions of affective functioning. To provide a quantitative summary of this literature, three conceptually related meta-analyses examined the effect of sleep restriction and sleep deprivation on mood, emotion, and emotion regulation across the lifespan (i.e. from early childhood to late adulthood).

METHODS

A total of 241 effect sizes from 64 studies were selected for inclusion, and multilevel meta-analytic techniques were used when applicable.

RESULTS

There was a moderate, positive effect of sleep loss on negative mood (g = 0.45), which was stronger for studies with younger samples, as well as a large, negative effect of sleep loss on positive mood (g = -0.94). For negative mood only, studies that used total sleep deprivation had larger effect sizes than studies that restricted sleep. After correcting for publication bias, a modest but significant negative effect for sleep loss on emotion (g = -0.11) was found; the valence of emotional stimuli did not change the direction of this effect, and type of sleep manipulation was also not a significant moderator. Finally, sleep restriction had a small, negative effect on adaptive emotion regulation (g = -0.32), but no significant impact on maladaptive emotion regulation (g = 0.14); all studies on adaptive emotion regulation were conducted with youth samples.

CONCLUSIONS

Sleep loss compromises optimal affective functioning, though the magnitude of effects varies across components. Findings underscore the importance of sleep for healthy affective outcomes.

Sleep duration and mood in adolescents: an experimental study

STUDY OBJECTIVES

This study examines the relationship between experimentally manipulated sleep duration and mood in adolescents.

METHODS

Thirty-four adolescents (20 male), aged 15-17 years, lived in a sleep laboratory for 10 days and 9 nights. They were allocated to one of three sleep "doses" for five consecutive nights for 5, 7.5, or 10 h sleep opportunity per night. Two baseline nights and two recovery nights entailed 10 h sleep opportunity per night. Mood was measured every 3 h during wake using unipolar visual analogue scales measuring the mood states "depressed," "afraid," "angry," "confused," "anxious," "happy," and "energetic."

RESULTS

Mixed models analyses with post hoc comparisons revealed that participants in the 5-h group, but not the 7.5- or 10-h groups, reported being significantly more depressed, angry, and confused during sleep restriction than at baseline. Adolescents were significantly less happy and energetic during sleep restricted to 5 h and significantly less energetic during sleep restricted to 7.5 h. When adolescents had 10 h sleep opportunities their happiness significantly increased. No statistically significant effects of sleep restriction were found for fear or anxiety, although small-to-moderate effects of sleep restricted to 5 or 7.5 h were found. Two nights of recovery sleep was not sufficient to recover from increased negative mood states for the 5-h group, although recovery occurred for positive mood states.

CONCLUSIONS

Given the prevalence of insufficient sleep and the rising incidence of mood disorders and dysregulation in adolescents, these findings highlight the importance of sufficient sleep to mitigate these risks.

Respiratory, cardiac, EEG, BOLD signals and functional connectivity over multiple microsleep episodes

Falling asleep is common in fMRI studies. By using long eyelid closures to detect microsleep onset, we showed that the onset and termination of short sleep episodes invokes a systematic sequence of BOLD signal changes that are large, widespread, and consistent across different microsleep durations. The signal changes are intimately intertwined with shifts in respiration and heart rate, indicating that autonomic contributions are integral to the brain physiology evaluated using fMRI and cannot be simply treated as nuisance signals. Additionally, resting state functional connectivity (RSFC) was altered in accord with the frequency of falling asleep and in a manner that global signal regression does not eliminate. Our findings point to the need to develop a consensus among neuroscientists using fMRI on how to deal with microsleep intrusions. SIGNIFICANCE STATEMENT: Sleep, breathing and cardiac action are influenced by common brainstem nuclei. We show that falling asleep and awakening are associated with a sequence of BOLD signal changes that are large, widespread and consistent across varied durations of sleep onset and awakening. These signal changes follow closely those associated with deceleration and acceleration of respiration and heart rate, calling into question the separation of the latter signals as 'noise' when the frequency of falling asleep, which is commonplace in RSFC studies, correlates with the extent of RSFC perturbation. Autonomic and central nervous system contributions to BOLD signal have to be jointly considered when interpreting fMRI and RSFC studies.

Chronic sleep restriction triggers inadequate napping habits in adolescents: a population-based study

BACKGROUND

The prevalence of chronic sleep restriction during adolescence is a major public health issue. Napping has been adopted to alleviate sleep pressure complaints. However, it also has the potential to amplify sleep restriction due to a vicious cycle triggered by delayed sleep times. The aim of this study was to investigate sleep and napping habits in a sample of Brazilian adolescents.

METHODS

This study enrolled 1554 high school students and included the evaluation of sleep times, daytime sleepiness, sleep quality, and circadian preference. The students were asked about their napping routine, ie its frequency and duration per week.

RESULTS

The adolescent sleep recommendation was achieved by only 27.6% of the sample. Napping habit was reported by 58.1%, with 36.2% of nappers informing naps in 1-2 times per week. Prolonged naps were reported by 44.9% of nappers. Nappers had later median bedtime (23:30) and reduced time in bed (TIB) (median = 07:00 h) compared to non-nappers. The frequency of nappers who did not achieve satisfactory TIB was higher than non-nappers. In addition, nappers reported increased daytime sleepiness and poor sleep quality. Later bedtimes and reduced TIB were associated with longer nap duration. Increased sleepiness and poor sleep quality were linked to a higher nap frequency.

CONCLUSIONS

This exploratory survey demonstrated a severe sleep restriction faced by Brazilian adolescents. Napping can be an efficient strategy to counteract sleep restriction, but it needs to be adopted with caution due to the detrimental effects of frequent and prolonged naps on nocturnal sleep.

New insights into the cognitive effects of sleep deprivation by decomposition of a cognitive throughput task

STUDY OBJECTIVES

A cognitive throughput task known as the Digit Symbol Substitution Test (DSST) (or Symbol Digit Modalities Test) has been used as an assay of general cognitive slowing during sleep deprivation. Here, the effects of total sleep deprivation (TSD) on specific cognitive processes involved in DSST performance, including visual search, spatial memory, paired-associate learning, and motor response, were investigated through targeted task manipulations.

METHODS

A total of 12 DSST variants, designed to manipulate the use of specific cognitive processes, were implemented in two laboratory-based TSD studies with N = 59 and N = 26 subjects, respectively. In each study, the Psychomotor Vigilance Test (PVT) was administered alongside the DSST variants.

RESULTS

TSD reduced cognitive throughput on all DSST variants, with response time distributions exhibiting rightward skewing. All DSST variants showed practice effects, which were however minimized by inclusion of a pause between trials. Importantly, TSD-induced impairment on the DSST variants was not uniform, with a principal component analysis revealing three factors. Diffusion model decomposition of cognitive processes revealed that inter-individual differences during TSD on a two-alternative forced choice DSST variant were different from those on the PVT.

CONCLUSIONS

While reduced cognitive throughput has been interpreted to reflect general cognitive slowing, such TSD-induced impairment appears to reflect cognitive instability, like on the PVT, rather than general slowing. Further, comparisons between task variants revealed not one, but three distinct underlying processes impacted by sleep deprivation. Moreover, the practice effect on the task was found to be independent of the TSD effect and minimized by a task pacing manipulation.

A daytime nap restores hippocampal function and improves declarative learning

STUDY OBJECTIVES

Daytime naps can confer benefits on subsequent declarative learning, but the physiological correlates of this improvement are less well studied. We examined learning following a daytime nap compared with an equivalent waking period using fMRI and polysomnography.

METHODS

Forty healthy young adults who slept normally the previous night encoded word pair lists in an MRI scanner at 13:00 and 16:30. Between sessions, participants either stayed awake and watched a documentary (Wake Group; N = 20) or had a 90-minute nap opportunity (Nap Group; N = 20) monitored by polysomnography. Approximately 40 minutes after completing each encoding session, memory for learned words was assessed using cued-recall.

RESULTS

A significant Session × Group interaction effect (p < 0.001) was observed in which memory was significantly improved in the Nap but not in the Wake group (p < 0.001). There was also a Session × Run × Group interaction effect in the left hippocampus (p = 0.001), whereby activation during word pair encoding increased only following the nap. Both performance improvement (rs = 0.46, p = 0.04) and nap-related increase in hippocampal activation (rs = 0.46, p = 0.04) were correlated with nap spindle count (12-15 Hz) but not with slow oscillation power (p's ≥ 0.18).

CONCLUSIONS

After a habitual nocturnal sleep, participants who had a 90-minute afternoon nap encoded word pairs better than a comparable group who stayed awake. Increases in hippocampal activation following the nap suggest restored hippocampal function. Naptime spindles may contribute to improved memory.

Cognitive effects of split and continuous sleep schedules in adolescents differ according to total sleep opportunity

STUDY OBJECTIVES

We compared the basic cognitive functions of adolescents undergoing split (nocturnal sleep + daytime nap) and continuous nocturnal sleep schedules when total sleep opportunity was either below or within the recommended range (i.e. 6.5 or 8 h).

METHODS

Adolescent participants (age: 15-19 year) in the 8-h split (n = 24) and continuous (n = 29) sleep groups were compared with 6.5-h split and continuous sleep groups from a previous study (n = 58). These protocols involved two baseline nights (9-h time-in-bed [TIB]), 5 nights of sleep manipulation, 2 recovery nights (9-h TIB), followed by a second cycle of sleep manipulation (3 nights) and recovery (2 nights). Cognitive performance, subjective sleepiness, and mood were evaluated daily; sleep was assessed using polysomnography.

RESULTS

Splitting 6.5 h of sleep with a mid-afternoon nap offered a boost to cognitive function compared to continuous nocturnal sleep. However, when total TIB across 24 h increased to 8 h, the split and continuous sleep groups performed comparably in tests evaluating vigilance, working memory, executive function, processing speed, subjective sleepiness, and mood.

CONCLUSIONS

In adolescents, the effects of split sleep on basic cognitive functions vary by the amount of total sleep obtained. As long as the total sleep opportunity across 24 h is within the recommended range, students may fulfill sleep requirements by adopting a split sleep schedule consisting of a shorter period of nocturnal sleep combined with a mid-afternoon nap, without significant impact on basic cognitive functions.

CLINICAL TRIAL REGISTRATION

NCT04044885.

Decreased P2 Waveform Reflects Impaired Brain Executive Function Induced by 12 h of Low Homeostatic Sleep Pressure: Evidence From an Event-Related Potential Study

Homeostatic sleep pressure can cause cognitive impairment, in which executive function is the most affected. Previous studies have mainly focused on high homeostatic sleep pressure (long-term sleep deprivation); thus, there is still little related neuro-psycho-physiological evidence based on low homeostatic sleep pressure (12 h of continuous wakefulness) that affects executive function. This study aimed to investigate the impact of lower homeostatic sleep pressure on executive function. Our study included 14 healthy young male participants tested using the Go/NoGo task in normal resting wakefulness (10:00 am) and after low homeostatic sleep pressure (10:00 pm). Behavioral data (response time and accuracy) were collected, and electroencephalogram (EEG) data were recorded simultaneously, using repeated measures analysis of variance for data analysis. Compared with resting wakefulness, the participants' response time to the Go stimulus was shortened after low homeostatic sleep pressure, and the correct response rate was reduced. Furthermore, the peak amplitude of Go-P2 decreased significantly, and the peak latency did not change significantly. For NoGo stimulation, the peak amplitude of NoGo-P2 decreased significantly (p < 0.05), and the peak latency was significantly extended (p < 0.05). Thus, the P2 wave is likely related to the attention and visual processing and reflects the early judgment of the perceptual process. Therefore, the peak amplitude of Go-P2 and NoGo-P2 decreased, whereas the peak latency of NoGo-P2 increased, indicating that executive function is impaired after low homeostatic sleep pressure. This study has shown that the P2 wave is a sensitive indicator that reflects the effects of low homeostatic sleep pressure on executive function, and that it is also an important window to observe the effect of homeostatic sleep pressure and circadian rhythm on cognitive function.

How much sleep do you need? A comprehensive review of fatigue related impairment and the capacity to work or drive safely

In developed countries, deaths attributable to driving or working while intoxicated have steadily declined over recent decades. In part, this has been due to (a) public education programs about the risks and (b) the deterrence value associated with penalties and prosecutions based on an individual being 'deemed impaired' if they exceed a proscribed level of blood alcohol or drug concentration while driving/working. In contrast, the relative proportion of fatigue-related accidents have remained stubbornly high despite significant public and workplace education. As such, it may be useful to introduce the legal principle of 'deemed impaired' with respect to fatigue and/or sleep loss. A comprehensive review of the impairment and accident literature was performed, including 44 relevant publications. Findings from this review suggests that a driver or worker might reasonably be 'deemed impaired' once the amount of sleep falls below five hours in the prior 24. Building on the legal principles first outlined in recent New Jersey legislation (Maggie's Law), this review argues that an individual can reasonably be 'deemed impaired' based on prior sleep wake behaviour. In Maggie's Law, a driver can be indirectly 'deemed impaired' if they have not slept in the prior 24 h. Based on the extant literature, we argue that, relative to drug and alcohol intoxication, this may be overly conservative. While roadside measurement of fatigue and prior sleep-wake behavior is not yet possible, we suggest that public education programs should provide specific guidance on the amount of sleep required and that post-accident forensic examination of prior sleep wake behaviours may help the community to determine unsafe behaviours and liability more objectively than is currently the case.

Large cognitive fluctuations surrounding sleep in daily living

Cognitive output and physical activity levels fluctuate surrounding sleep. The ubiquitous digitization of behavior via smartphones is a promising avenue for addressing how these fluctuations occur in daily living. Here, we logged smartphone touchscreen interactions to proxy cognitive fluctuations and contrasted these to physical activity patterns logged on wrist-worn actigraphy. We found that both cognitive and physical activities were dominated by diurnal (∼24 h) and infra-radian (∼7 days) rhythms. The proxy measures of cognitive performance—tapping speed, unlocking speed, and app locating speed—contained lower-powered diurnal rhythm than physical activity. The difference between cognitive and physical activity was vivid during bedtime as people continued to interact with their smartphones at physical rest. The cognitive performance measures in this period were worse than those in the hour before or after bedtime. We suggest that the rhythms underlying cognitive activity in the real world are distinct from those underlying physical activity, and this discord may be a hallmark of modern human behavior.

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Daily and weekly rhythms shape our day-to-day behavior

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The speed of smartphone interactions fluctuates according to the time of the day

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These fluctuations do not strictly follow the physical activity cycles

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The worst performing time on the smartphone is around bedtime

Waking Activities and Sleep: Analysis of United Kingdom Adolescents' Daily Time-Use Diaries

PURPOSE

To investigate waking activities associated with risks of short and long sleep in a representative cohort of UK adolescents.

METHODS

Data from 14-year-olds participating in the UK Millennium Cohort Study were used. Daily time-use diaries were completed by adolescents on two randomly selected days (one weekday and one weekend) to capture their activities within a 24-hour period from 4 a.m. of each selected day. Short and long sleep duration categories were defined as beyond the extreme lower and upper thresholds of acceptable age-specific sleep durations recommended by the National Sleep Foundation, respectively.

RESULTS

Approximately 8% and 6% were short sleepers on weekdays and weekends, respectively. On average, adolescents spent 33% of their time awake per weekend day on recreational digital media activities. Compared with those who had optimal sleep on weekdays, short sleepers spent more time on personal care (mean difference = +56 minutes; 95% confidence interval [CI]: 21; 92) and less time on exercise activities (mean difference = -15 minutes; 95% CI: -27; -3). Ten-minute increase in daily digital media activity was associated with 2% (95% CI: 1.01; 1.03) higher relative risk of adolescents being short sleepers on weekdays. Relative risk of short sleeping was 1.03 (95% CI: 1.01; 1.04) times higher for every10-minute daily increase in travel time on weekdays.

CONCLUSIONS

Adolescents spend up to one-third of their time awake per day on digital media. However, more time spent on personal care and travel on weekdays and weekends is associated with increased risk of short sleep. These findings permit a reflection on appropriate interventions needed to improve sleep duration in sleep-deprived teens.

The Treatment of Sleep Dysfunction in Neurodegenerative Disorders

Sleep dysfunction is highly prevalent across the spectrum of neurodegenerative conditions and is a key determinant of quality of life for both patients and their families. Mounting recent evidence also suggests that such dysfunction exacerbates cognitive and affective clinical features of neurodegeneration, as well as disease progression through acceleration of pathogenic processes. Effective assessment and treatment of sleep dysfunction in neurodegeneration is therefore of paramount importance; yet robust therapeutic guidelines are lacking, owing in part to a historical paucity of effective treatments and trials. Here, we review the common sleep abnormalities evident in neurodegenerative disease states and evaluate the latest evidence for traditional and emerging interventions, both pharmacological and nonpharmacological. Interventions considered include conservative measures, targeted treatments of specific clinical sleep pathologies, established sedating and alerting agents, melatonin, and orexin antagonists, as well as bright light therapy, behavioral measures, and slow-wave sleep augmentation techniques. We conclude by providing a suggested framework for treatment based on contemporary evidence and highlight areas that may emerge as major therapeutic advances in the near future.

Multi-Night Validation of a Sleep Tracking Ring in Adolescents Compared with a Research Actigraph and Polysomnography

BACKGROUND

Wearable devices have tremendous potential for large-scale longitudinal measurement of sleep, but their accuracy needs to be validated. We compared the performance of the multisensor Oura ring (Oura Health Oy, Oulu, Finland) to polysomnography (PSG) and a research actigraph in healthy adolescents.

METHODS

Fifty-three adolescents (28 females; aged 15-19 years) underwent overnight PSG monitoring while wearing both an Oura ring and Actiwatch 2 (Philips Respironics, USA). Measurements were made over multiple nights and across three levels of sleep opportunity (5 nights with either 6.5 or 8h, and 3 nights with 9h). Actiwatch data at two sensitivity settings were analyzed. Discrepancies in estimated sleep measures as well as sleep-wake, and sleep stage agreements were evaluated using Bland-Altman plots and epoch-by-epoch (EBE) analyses.

RESULTS

Compared with PSG, Oura consistently underestimated TST by an average of 32.8 to 47.3 minutes (Ps < 0.001) across the different TIB conditions; Actiwatch 2 at its default setting underestimated TST by 25.8 to 33.9 minutes. Oura significantly overestimated WASO by an average of 30.7 to 46.3 minutes. It was comparable to Actiwatch 2 at default sensitivity in the 6.5, and 8h TIB conditions. Relative to PSG, Oura significantly underestimated REM sleep (12.8 to 19.5 minutes) and light sleep (51.1 to 81.2 minutes) but overestimated N3 by 31.5 to 46.8 minutes (Ps < 0.01). EBE analyses demonstrated excellent sleep-wake accuracies, specificities, and sensitivities - between 0.88 and 0.89 across all TIBs.

CONCLUSION

The Oura ring yielded comparable sleep measurement to research grade actigraphy at the latter's default settings. Sleep staging needs improvement. However, the device appears adequate for characterizing the effect of sleep duration manipulation on adolescent sleep macro-architecture.

What Factors Are Most Closely Associated With Mood Disorders in Adolescents During the COVID-19 Pandemic? A Cross-Sectional Study Based on 1,771 Adolescents in Shandong Province, China

Background and Aims: COVID-19 has been proven to harm adolescents' mental health, and several psychological influence factors have been proposed. However, the importance of these factors in the development of mood disorders in adolescents during the pandemic still eludes researchers, and practical strategies for mental health education are limited. Methods: We constructed a sample of 1,771 adolescents from three junior high middle schools, three senior high middle schools, and three independent universities in Shandong province, China. The sample stratification was set as 5:4:3 for adolescent aged from 12 - 15, 15 - 18, 18 - 19. We examined the subjects' anxiety, depression, psychological resilience, perceived social support, coping strategies, subjective social/school status, screen time, and sleep quality with suitable psychological scales. We chose four widely used classification models-k-nearest neighbors, logistic regression, gradient-boosted decision tree (GBDT), and a combination of the GBDT and LR (GBDT + LR)-to construct machine learning models, and we utilized the Shapley additive explanations value (SHAP) to measure how the features affected the dependent variables. The area under the curve (AUC) of the receiver operating characteristic (ROC) curves was used to evaluate the performance of the models. Results: The current rates of occurrence of symptoms of anxiety and depression were 28.3 and 30.8% among the participants. The descriptive and univariate analyses showed that all of the factors included were statistically related to mood disorders. Among the four machine learning algorithms, the GBDT+LR algorithm achieved the best performance for anxiety and depression with average AUC values of 0.819 and 0.857. We found that the poor sleep quality was the most significant risk factor for mood disorders among Chinese adolescents. In addition, according to the feature importance (SHAP) of the psychological factors, we proposed a five-step mental health education strategy to be used during the COVID-19 pandemic (sleep quality-resilience-coping strategy-social support-perceived social status). Conclusion: In this study, we performed a cross-sectional investigation to examine the psychological impact of COVID-19 on adolescents. We applied machine learning algorithms to quantify the importance of each factor. In addition, we proposed a five-step mental health education strategy for school psychologists.

When Night Falls Fast: Sleep and Suicidal Behavior Among Adolescents and Young Adults

Sleep disturbances have been linked to suicidal ideation and behaviors in adolescents. Specifically, insomnia and nightmares are associated with current suicide risk and predict future ideation. Associations between hypersomnia, sleep apnea, and suicide remain inconclusive. Potential biological mechanisms underlying these relationships include executive functioning deficits and hyperarousal. Related psychological factors may include thwarted belongingness, perceived burdensomeness, and negative appraisals. Assessing suicide risk in patients with sleep disturbances, and vice versa, is needed. Therapeutic interventions such as cognitive behavior therapy for insomnia and imagery rehearsal treatment, as well as pharmacologic treatments, show promise in treating sleep disorders and suicidal behavior.

Morning brain: real-world neural evidence that high school class times matter

Researchers, parents and educators consistently observe a stark mismatch between biologically preferred and socially imposed sleep-wake hours in adolescents, fueling debate about high school start times. We contribute neural evidence to this debate with electroencephalogram data collected from high school students during their regular morning, mid-morning and afternoon classes. Overall, student alpha power was lower when class content was taught via videos than through lectures. Students' resting state alpha brain activity decreased as the day progressed, consistent with adolescents being least attentive early in the morning. During the lessons, students showed consistently worse performance and higher alpha power for early morning classes than for mid-morning classes, while afternoon quiz scores and alpha levels varied. Together, our findings demonstrate that both class activity and class time are reflected in adolescents' brain states in a real-world setting, and corroborate educational research suggesting that mid-morning may be the best time to learn.

Neurobehavioural functions during variable and stable short sleep schedules

We investigated whether variable sleep schedules might mitigate the neurobehavioural deficits induced by multiple nights of sleep restriction. In this 4-night experiment, 78 young adults (age: 18-28 years) were randomly assigned to four groups: 8888, 8666, 8846 and 8486, where each digit corresponded to time-in-bed in hours for each study night. After one baseline night of 8-hr time-in-bed, time-in-bed remained unchanged for the 8888 group, while the other groups had short sleep schedules (total time-in-bed = 18 hr) that differed in the number of time-in-bed changes. Sleep was monitored using actigraphy at home. Daytime neurobehavioural functions were assessed in the laboratory at single time points, after the baseline night, and again after 3 nights of the sleep manipulation period. For sustained attention, the 8888 group responded faster in the Psychomotor Vigilance Task after the manipulation period (p = .01), while responses became slower for the less variable sleep schedules (8666 and 8846; p < .01), but not the most variable sleep schedule (8486; p = .14). Processing speed also improved in the 8888 group and the variable 8846 and 8486 groups (p < .01), but not in the stable 8666 group (p = .09). Furthermore, subjective sleepiness was preserved in the 8888 and, importantly, 8486 groups (p > .05), but was elevated in the 8666 and 8846 groups (p < .05). These findings suggest that when sleep opportunities are limited across multiple nights, a variable sleep schedule that allows for prophylactic and/or recovery sleep on some nights may mitigate some daytime neurobehavioural deficits as compared with a schedule with no opportunity for recovery.

Association between free-living sleep and memory and attention in healthy adolescents

In laboratory studies, imposed sleep restriction consistently reduces cognitive performance. However, the association between objectively measured, free-living sleep and cognitive function has not been studied in older adolescents. To address this gap, we measured one week of sleep with a wrist-worn GT3X+ actigraph in 160 adolescents (96 girls, 17.7 ± 0.3 years) followed by assessment of working memory with an n-back task and visual attention with a Posner cue-target task. Over the week, participants spent 7.1 ± 0.8 h/night in bed and slept 6.2 ± 0.8 h/night with 88.5 ± 4.8% efficiency and considerable intra-participant night-to-night variation, with a standard deviation in sleep duration of 1.2 ± 0.7 h. Sleep measures the night before cognitive testing were similar to weekly averages. Time in bed the night before cognitive testing was negatively associated with response times during the most challenging memory task (3-back; p = 0.005). However, sleep measures the night before did not correlate with performance on the attention task and weekly sleep parameters were not associated with either cognitive task. Our data suggests shorter acute free-living sleep may negatively impact difficult memory tasks, however the relationship between free-living sleep and cognitive task performance in healthy adolescents is less clear than that of laboratory findings, perhaps due to high night-to-night sleep variation.

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.

Caffeine intake and cognitive functions in children

RATIONALE

There is a growing concern over excessive caffeine use and development of caffeine use disorder in children.

OBJECTIVES

This study aimed to identify the association between caffeine intake and cognitive functioning in children.

METHODS

This study included 11,718 youths aged 9-10 years with cognitive and caffeine intake information that were extracted from the Adolescent Brain Cognitive Development (ABCD) study. The ABCD study is a longitudinal cohort study started in 2017 that aims to understand the relationships between substance use and neurocognition in youths living in the USA. Cognitive measures were obtained through the 7 core cognitive instruments from the NIH toolbox (vocabulary comprehension, reading decoding, inhibitory control, working memory, cognitive flexibility, processing speed, and episodic memory). Associations between caffeine intake and the seven cognitive functions were examined using multiple regression models.

RESULTS

Our study revealed that caffeine intake negatively correlated with all the seven cognitive measures. After adjustment for age, gender, sleep, and socioeconomic status (SES), caffeine intake was still found to be negatively associated with most of the cognitive functions, such as vocabulary comprehension, working memory, cognitive flexibility, processing speed, and episodic memory, except reading decoding, and inhibitory control.

CONCLUSIONS

As beverages with caffeine are consumed frequently, controlling their intake may reduce a risk for nonoptimal cognitive development in children.

Impact of sleep restriction on affective functioning in adolescents with attention-deficit/hyperactivity disorder

BACKGROUND

Shortened sleep and affective disturbances are both prevalent in adolescents with attention-deficit/hyperactivity disorder (ADHD), yet the causal link between these domains has not been examined. This study investigated whether shortened sleep duration is causally linked to affective functioning in adolescents with ADHD.

METHODS

Participants were 48 adolescents (75% male) aged 14-17 years with ADHD who successfully completed a three-week sleep protocol using an experimental crossover design. The protocol included a phase stabilization week, followed, in randomized counterbalanced order, by one week of sleep restriction (6.5 hr in bed) and one week of sleep extension (9.5 hr in bed). Sleep was monitored with objective actigraphy, and all participants included in this study obtained ≥1 hr actigraphy-measured sleep duration during extension compared to restriction. Parents and adolescents provided daily ratings of positive and negative affect during the extension and restriction conditions. Ratings of affect, internalizing symptoms, and emotion regulation were collected at laboratory visits conducted at the end of each week.

RESULTS

Both parents and adolescents reported greater depressive symptoms and lower positive affect during restriction compared to extension. Parents also reported greater negative affect and emotion dysregulation among adolescents during sleep restriction than extension. No effects were found for parent- or adolescent-reported anxiety symptoms or for adolescent-reported emotion regulation or negative affect.

CONCLUSIONS

Findings from this study provide the first evidence that shortened sleep duration is a causal contributor to the affect and mood disturbances frequently experienced by adolescents with ADHD, particularly as observed by parents. Targeting sleep may be important to reduce affective disturbances in adolescents with ADHD.

The impact of reduced sleep on school related outcomes for typically developing children aged 11–19: A systematic review

This systematic literature review examines the relationship between restricted and reduced sleep and school performance, learning and cognitive functioning in typically developing adolescents. Correlational and experimental data were evaluated from 17 studies which included participants ranging from 11 to 19 years in studies from seven countries around the world. The review found that there is evidence that restricted and reduced sleep is negatively associated with school performance and cognitive outcomes, although the findings were mixed. Implications for psychologists working with schools are discussed. More research and evaluation is needed to establish how these factors relate to each other conclusively.

Sleepiness, Neuropsychological Skills, and Scholastic Learning in Children

Excessive daytime sleepiness is a frequent condition among children and adolescents that may lead to several and significant daytime consequences, including impaired neurocognitive skills and scholastic performance. Here, we evaluated in one hundred and ninety-one unselected primary school children, the relationship between sleepiness and a wide range of cognitive and academic skills through a standardized neuropsychological test battery. In order to assess the statistical relationship, we performed a partial least squares path modelling, a non-parametrical approach which combined a model of paths between latent variables and the coefficients between indicators and dimensions. Results were validated through the bootstrap approach and suggest that sleepiness is not associated with all cognitive and scholastic abilities, but only with those relying on verbal abilities and complex cognitive functions (i.e., reading comprehension, oral/syntactic comprehension, spelling, and mathematic skills). Our data suggest the idea that sleepiness in children is associated mostly with “higher” (mainly verbal) cognitive function(s), while the visuospatial domain was not affected.

Sleep and development in adolescence in the context of socioeconomic disadvantage

INTRODUCTION

Sleep problems are associated with negative developmental outcomes in youth, and identification of vulnerability and protective factors is needed to explicate for whom and under which conditions adolescents may be most at risk. Towards this end, we examined socio-economic status (SES) as a moderator of associations between multiple sleep parameters and adolescents' socio-emotional adjustment and cognitive functioning.

METHODS

Participants were 272 adolescents (M age = 17.3 years; 49% girls) and their parents, residing in the Southeastern U.S.A. The sample was socioeconomically diverse and included 41% Black/African American and 59% White/European American youth. Using a cross-sectional design, adolescents' sleep was assessed with actigraphy (total sleep minutes; efficiency indicated by % of time asleep from sleep onset to wake time) and self-reports of sleep quality (sleep-wake problems). Mothers reported on youths' internalizing and externalizing symptoms, and cognitive functioning was assessed with a standardized test battery.

RESULTS

Moderation effects were found and illustrated that, for youth from families with lower SES, shorter and less efficient sleep and subjective sleep problems were associated with higher levels of internalizing and externalizing symptoms as well as lower cognitive performance. Conversely, longer and better-quality sleep protected against socio-emotional and cognitive difficulties otherwise observed for socioeconomically disadvantaged youth. Fewer relations between sleep and adjustment emerged for adolescents from families with higher SES.

CONCLUSIONS

Results reinforce a growing literature indicating that the relation between sleep and adjustment is stronger for youth from families with lower SES, who may especially benefit from better sleep.

Socioeconomic status and sleep in adolescence: The role of family chaos

Low socioeconomic status (SES) has been associated with poor sleep in youth, yet mechanisms underlying this association are not well-understood. The present study examined greater chaos as a mediator of associations between low SES and 2 indices of poor sleep. Two hundred fifty-two adolescents (53% girls; 66% White/European American, 34% Black/African American) participated in the 3-wave longitudinal study. The sample was socioeconomically diverse. At age 16, parents reported on 2 indices of SES: family income and perceived economic well-being. Adolescents reported on chaos within their family at age 17 and on 2 key sleep-wake processes-sleep quality and daytime sleepiness-at age 18. Family chaos functioned as a mediating or intervening variable in longitudinal associations between lower SES and both poorer sleep quality and greater daytime sleepiness. The findings suggest the potential utility of targeting family level processes that exemplify chaos, such as unpredictability, noise, and interruptions, to improve sleep among adolescents. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Growing up strong: The importance of physical, mental, and emotional strength during childhood and adolescence with focus on dietary factors

Childhood and adolescence are critical time periods for growth and development. Given the current physical and psychological health concerns affecting United States youth, an emerging area of interest exists supporting the importance of physical and psychological aspects of strength for health, resilience, and well-being through these life stages. This synopsis highlights the key concepts that were presented within the 2018 Strength Summit conference, entitled The Role of Strength in Optimal Health and Well-being. During the conference, strength was broadly defined as the ability to successfully respond to a challenge. Although much of the current research focuses on strength from a muscle function and performance perspective, mental and emotional strength are also important components of overall health and well-being, especially in children and adolescents. This paper provides a brief overview of the clinical and/or research-based strength outcomes, summarizes the relationship between strength and health, and discusses evidence-based dietary factors that promote strength in children and adolescents. Novelty Building physical, mental, and emotional strength during childhood and adolescence lays the foundation for health and well-being. Emerging evidence indicate positive associations between diet quality and strength in children and adolescents. Promising areas include the promotion of family-based meals, with focus on breakfast, for improved strength in United States youth.

A systematic review and meta-analysis of behavioral sleep interventions for adolescents and emerging adults

In the United States, more than two-thirds of adolescents and one-third of emerging adults report habitual short sleep duration, which is a known risk factor for psychological distress. The primary aim of this systematic review and meta-analysis was to evaluate the effect of behavioral sleep-promoting interventions on the sleep characteristics (e.g., total sleep time and sleep efficiency) of adolescents and emerging adults (aged 12-25 y) who do not have a sleep disorder. The secondary aim was to determine the effect of behavioral sleep-promoting interventions on psychological distress. Multiple electronic databases were searched for relevant randomized controlled trials (RCTs) published in English. Fourteen RCTs were included in the qualitative synthesis (N = 932), seven were included in the meta-analysis (n = 711) to address the primary aim, and three (n = 253) were included to address the secondary aim. The pooled standardized mean difference for sleep-promoting interventions after treatment for total sleep time was 34.92 min (95% CI: 8.70, 61.14). Sleep-promoting interventions had no significant effect on sleep efficiency. More RCTs that involve adolescents and emerging adults are needed to determine the effect of sleep-promoting interventions on reducing psychological distress in this high-risk age group.

Associations of time spent on homework or studying with nocturnal sleep behavior and depression symptoms in adolescents from Singapore

OBJECTIVE

To investigate associations of adolescents' time spent on homework/studying with nocturnal time for sleep and depression symptoms, in a competitive academic environment.

DESIGN

Cross-sectional, anonymous survey of sleep habits, school life, and health-related measures.

SETTING

Eight schools in Singapore.

PARTICIPANTS

Total 1225 adolescents aged 13-19 years.

MEASUREMENTS

Self-reported sleep behavior and time use data were collected separately for school days and weekends. Multiple regression models were used to test covariation of time spent on homework/studying with other activities, and associations of homework/studying duration with depression symptoms.

RESULTS

Time in bed for sleep and media use were inversely related with homework/studying duration on both school days and weekends, adjusting for time spent on other activities and demographic variables. Face-to-face family time and hanging out with friends were also reciprocally related with homework/studying duration on weekends. Depression scores were higher in adolescents who spent long hours on homework/studying. On school days, this was mediated by reduced time in bed for sleep. On weekends, homework/studying duration associated with depression symptoms, adjusting for time in bed and other covariates. Adolescents who spent ≥5 hours on homework/studying per day on weekends had greater symptoms of anhedonia and anxiety.

CONCLUSIONS

In a competitive academic setting, adolescents who spent more time on homework/studying spent less time on sleep, media use, and social activities. Independent of effects on sleep, long hours on homework/studying on weekends may be a risk factor for depression. Reducing adolescents' workload outside of class may benefit their sleep, schoolwork-life balance, and mental well-being.

Autonomic Activity during a Daytime Nap Facilitates Working Memory Improvement

Recent investigations have implicated the parasympathetic branch of the autonomic nervous system in higher-order executive functions. These actions are purported to occur through autonomic nervous system's modulation of the pFC, with parasympathetic activity during wake associated with working memory (WM) ability. Compared with wake, sleep is a period with substantially greater parasympathetic tone. Recent work has reported that sleep may also contribute to improvement in WM. Here, we examined the role of cardiac parasympathetic activity during sleep on WM improvement in healthy young adults. Participants were tested in an operation span task in the morning and evening, and during the intertest period, participants experienced either a nap or wake. We measured high-frequency heart rate variability as an index of cardiac, parasympathetic activity during both wake and sleep. Participants showed the expected boost in parasympathetic activity during nap, compared with wake. Furthermore, parasympathetic activity during sleep, but not wake, was significantly correlated with WM improvement. Together, these results indicate that the natural boost in parasympathetic activity during sleep may benefit gains in prefrontal executive function in young adults. We present a conceptual model illustrating the interaction between sleep, autonomic activity, and prefrontal brain function and highlight open research questions that will facilitate understanding of the factors that contribute to executive abilities in young adults as well as in cognitive aging.

Changes in sleep and activity from age 15 to 17 in students with traditional and college-style school schedules

OBJECTIVES

Sleep duration and physical activity decline with age during adolescence. Earlier school schedules may contribute to these declines. The aim of this longitudinal study was to track changes in sleep and activity of Icelandic youth from primary to secondary school and compare students who enrolled in secondary schools with traditional and college-style schedules.

METHODS

We measured free-living sleep and activity with wrist actigraphy and body composition by dual-energy x-ray absorptiometry in 145 students at age 15 and age 17, when 58% attended schools with college-style scheduling. Differences from 15 to 17 and between students of different school structures were assessed with mixed-effect models.

RESULTS

Actigraphs were worn for 7.1 ± 0.4 nights at 15 and 6.9 ± 0.4 nights at 17. Overall, sleep duration decreased from 6.6 ± 0.7 h/night to 6.2 ± 0.7 h/night from age 15 to 17 (P < .001). Students with traditional schedules reduced school-night sleep duration 26 min/night at follow-up (P< .001), while sleep duration did not change for college-style students. All students went to bed later on school nights at follow-up, but only college-style students rose later. Sleep efficiency and awakenings did not differ by schedule-type. Neither sex changed body fat percentage, but average school-day activity decreased by 19% (P< .001) on follow-up and did not differ by schedule-type.

CONCLUSIONS

Over the 2-year period, adolescents decreased weekly sleep duration and activity, but only those continuing traditional schedules reduced school-night sleep. This suggests greater individual control of school schedule may preserve sleep duration in this age group, which may be beneficial during the transition into adulthood.

Two nights of recovery sleep restores hippocampal connectivity but not episodic memory after total sleep deprivation

Sleep deprivation significantly impairs a range of cognitive and brain function, particularly episodic memory and the underlying hippocampal function. However, it remains controversial whether one or two nights of recovery sleep following sleep deprivation fully restores brain and cognitive function. In this study, we used functional magnetic resonance imaging (fMRI) and examined the effects of two consecutive nights (20-hour time-in-bed) of recovery sleep on resting-state hippocampal connectivity and episodic memory deficits following one night of total sleep deprivation (TSD) in 39 healthy adults in a controlled in-laboratory protocol. TSD significantly reduced memory performance in a scene recognition task, impaired hippocampal connectivity to multiple prefrontal and default mode network regions, and disrupted the relationships between memory performance and hippocampal connectivity. Following TSD, two nights of recovery sleep restored hippocampal connectivity to baseline levels, but did not fully restore memory performance nor its associations with hippocampal connectivity. These findings suggest that more than two nights of recovery sleep are needed to fully restore memory function and hippocampal-memory associations after one night of total sleep loss.

The impact of short sleep on food reward processes in adolescents

Short sleep has been linked to adolescent risk of obesity, but questions remain regarding the dietary mechanisms by which this occurs. We tested whether mildly shortening sleep influences how rewarding and appealing healthy adolescents find several kinds of foods. Eighty-eight healthy adolescents completed a within-subjects crossover sleep experiment comparing 5 days of Short Sleep (6.5 hr sleep opportunity) with 5 days of Healthy Sleep (9.5 hr sleep opportunity). Following each condition, adolescents completed measures of food appeal and reinforcing value of food across five food types: sweets/desserts, fruits/vegetables, lean meats/eggs, fast food and processed snacks. Adolescents averaged 2.2 hr/night longer sleep periods in Healthy Sleep versus Short Sleep. We observed a significant interaction of experimental order with sleep condition on three of four primary outcomes related to the appeal and reinforcing value of foods (p's < .005). When Short Sleep preceded Healthy Sleep, adolescents endorsed significantly greater appeal (p < .04) and rewarding value of food (p's ranging from <.01 to .048) during Short Sleep (compared to Healthy Sleep). However, when Healthy Sleep preceded Short Sleep, we did not observe a main effect of sleep condition on the same outcomes (p's > .05). This study provides evidence that restricting adolescents' sleep opportunity to 6.5 hr (compared to sleeping a healthy amount) increases the appeal and reinforcing value of a variety of foods, but this may occur only under protracted short sleep. Increased food reward may be one mechanism linking chronically shortened sleep with risk of obesity in adolescence.