Evidence that electroencephalography (EEG) slow-wave activity (SWA) (EEG spectral power in the 1-4.5 Hz band) during non-rapid eye movement sleep (NREM) reflects plastic changes is increasing (Tononi and Cirelli, 2006). Regional assessment of gray matter development from neuroimaging studies reveals a posteroanterior trajectory of cortical maturation in the first three decades of life (Shaw et al., 2008). Our aim was to test whether this regional cortical maturation is reflected in regional changes of sleep SWA. We evaluated all-night high-density EEG (128 channels) in 55 healthy human subjects (2.4 -19.4 years) and assessed age-related changes in NREM sleep topography. As in adults, we observed frequency-specific topographical distributions of sleep EEG power in all subjects. However, from early childhood to late adolescence, the location on the scalp showing maximal SWA underwent a shift from posterior to anterior regions. This shift along the posteroanterior axis was only present in the SWA frequency range and remained stable across the night. Changes in the topography of SWA during sleep parallel neuroimaging study findings indicating cortical maturation starts early in posterior areas and spreads rostrally over the frontal cortex. Thus, SWA might reflect the underlying processes of cortical maturation. In the future, sleep SWA assessments may be used as a clinical tool to detect aberrations in cortical maturation.

Objective-The purpose of the study was to examine the relationship between self-reported sleep quality and sleep hygiene in Italian and American adolescents and to assess whether sleephygiene practices mediate the relationship between culture and sleep quality.Methods-Two nonprobability samples were collected from public schools in Rome, Italy, and Hattiesburg, Mississippi. Students completed the following self-report measures: Adolescent Sleep-Wake Scale, Adolescent Sleep Hygiene Scale, Pubertal Developmental Scale, and Morningness/Eveningness Scale.Results-The final sample included 776 Italian and 572 American adolescents 12 to 17 years old. Italian adolescents reported much better sleep hygiene and substantially better sleep quality than American adolescents. A moderate-to-strong linear relationship was found between sleep hygiene and sleep quality in both samples. Separate hierarchical multiple regression analyses were performed on both samples. Demographic and individual characteristics explained a significant proportion of the variance in sleep quality (Italians: 18%; Americans: 25%), and the addition of sleep-hygiene domains explained significantly more variance in sleep quality (Italians: 17%; Americans: 16%). A final hierarchical multiple regression analysis with both samples combined showed that culture (Italy versus United States) only explained 0.8% of the variance in sleep quality after controlling for sleep hygiene and all other variables.Conclusions-Cross-cultural differences in sleep quality, for the most part, were due to differences in sleep-hygiene practices. Sleep hygiene is an important predictor of sleep quality in Italian and American adolescents, thus supporting the implementation and evaluation of educational programs on good sleep-hygiene practices. Adolescence is a period characterized by important changes in cognitive, behavioral, social, and emotional functioning attributable to biological development (ie, puberty) and to new roles and demands in the familial and social milieu (eg, decreased parental involvement, increased academic requirements). There also are dramatic changes in sleep/wake patterns during adolescence, including a decrease in sleep duration, 1-3 a delay in the timing of sleep, 4,5 and an increasingly large discrepancy between weekday and weekend sleep patterns. 6-9 Sleep quality is reduced as well. 10 Community-and school-based studies conducted in Europe, Asia, and the United States suggest that between 6% and 37% of adolescents report difficulties on ≥1 of the following behavioral dimensions of sleep quality: going to bed, 11,12 falling asleep, 3,13-17 maintaining undisturbed sleep, 10,16-18 reinitiating sleep after nocturnal awakenings, 3,16,17 and returning to wakefulness in the morning. 7,9,15,17 Furthermore, up to 16% of adolescents are considered to have clinically significant insomnia. 16,19,20 There is ample evidence that inadequate sleep quantity and quality are linked to significant problems in several aspects of teenagers' lives. 5,8 Sleepiness ...

Summary Reduced exposure to daytime sunlight and increased exposure to electrical lighting at night leads to late circadian and sleep timing [1–3]. We have previously shown that exposure to a natural summer 14 hr 40 min:9 hr 20 min light-dark cycle entrains the human circadian clock to solar time, such that the internal biological night begins near sunset and ends near sunrise [1]. Here we show the beginning of the biological night and sleep occur earlier after a week exposure to a natural winter 9 hr 20 min:14 hr 40 min light-dark cycle as compared to the modern electrical lighting environment. Further, we find the human circadian clock is sensitive to seasonal changes in the natural light-dark cycle showing an expansion of the biological night in winter compared to summer—akin to that seen in non-humans [4–8]. We also show circadian and sleep timing occur earlier after spending a weekend camping in a summer 14 hr 39 min:9 hr 21 min natural light-dark cycle compared to a typical weekend in the modern environment. Weekend exposure to natural light was sufficient to achieve ~69% of the shift in circadian timing we previously reported after one week exposure to natural light [1]. These findings provide evidence that the human circadian clock adapts to seasonal changes in the natural light-dark cycle and is timed later in the modern environment in both winter and summer. Further, we demonstrate earlier circadian timing can be rapidly achieved through natural light exposure during a weekend spent camping.

Objective-To examine associations of child and family sociodemographic characteristics with preschooler bedtime routines.Method-We use parent-report data on 3,217 3-year-old children (48% black; 26% Hispanic; 26% white) from the Fragile Families and Child Wellbeing Study to examine whether child and family characteristics are associated with the presence, time, and consistency of bedtime routines.Results-Over 80% of sample children have a bedtime yet only two-thirds follow it. After extensive controls for maternal education, family structure, and other household characteristics, Black and Hispanic children have later bedtimes than white children and reduced odds of using regular bedtimes (by 22% and 29%, respectively) and using bedtime routines (by 47% and 33%, respectively). Low maternal education, increased household size, and poverty are associated with decreased use of parent-child interactive and hygiene-related bedtime routines.Conclusion-Children from disadvantaged households are less likely to have consistent bedtime routines than their more advantaged counterparts. This may contribute to later disparities in sleep quality, duration and timing, factors known to be associated with adverse behavioral, cognitive, and health outcomes. Keywordsbedtimes; bedtime routines; children; sleep For many young children, getting ready for bed involves a routine that facilitates the transition from wakefulness to sleep. Routines may include a combination of diaper changing/toileting, changing into sleep clothes, brushing teeth, reading a story, singing, and/or getting good-night kisses, among others. 1 The American Academy of Pediatrics recommends regular bedtimes and bedtime activities in order to cue children for falling asleep and help them associate the pre-bedtime period with the upcoming sleep period. 2 The use and enforcement of regular bedtimes and consistent, quiet bedtime routines are associated with improved success in going Lauren Hale, PhD (Corresponding Author), lhale@notes.cc.sunysb.edu, phone: 631-444-1007, fax: 631-444-3480. NIH Public AccessAuthor Manuscript J Dev Behav Pediatr. Author manuscript; available in PMC 2010 October 1. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript to bed, falling asleep, sleeping through the night, and waking in the morning, 3-9 which in turn is associated with better physical health, behavioral, and cognitive outcomes. 10-15 Thus, bedtime routines are an important behavioral component for the healthy sleep and development of preschool-age children. Understanding the correlates of positive sleep behaviors will help to identify potential mechanisms and develop interventions that may lead to improved sleep and well-being for children.Although evidence suggests that regular bedtimes and bedtime routines are commonly used with young children, existing studies have tended to use small to modest samples generally comprised of relatively advantaged, primarily white children. For example, one study of 100 middle-class white toddlers found that 93...

Given the pervasive use of screen-based media and the high prevalence of insufficient sleep among American youth and teens, this brief report summarizes the literature on electronic media and sleep and provides research recommendations. Recent systematic reviews of the literature reveal that the vast majority of studies find an adverse association between screen-based media consumption and sleep health, primarily via delayed bedtimes and reduced total sleep duration. The underlying mechanisms of these associations likely include: (a) time displacement (i.e., time spent on screens replaces time spent sleeping and other activities); (b) psychological stimulation based on media content; and (c) the effects of light emitted from devices on circadian timing, sleep physiology, and alertness. Much of our current understanding of these processes, however, is limited by cross-sectional, observational, and self-reported data. Further experimental and observational research is needed to elucidate how the digital revolution is altering sleep and circadian rhythms across development (infancy to adulthood) as pathways to poor health, learning, and safety outcomes (e.g., obesity, depression, risk taking).

Purpose of review To highlight the recent findings on sleep–obesity associations in children. We focus on sleep duration, sleep timing and chronotype, and describe the potential mechanisms underlying sleep–obesity associations. Recent findings Poor sleep is increasingly common in children and associations between short sleep duration in early childhood and obesity are consistently found. Less is known about the infancy period, and the findings in adolescents are inconsistent. Sleep timing patterns may also contribute to obesity risk. Variable and shifted sleep schedules and evening chronotypes have recently been linked to adiposity in adults; less is known about children. Further, there is little understanding regarding the mechanisms of association. The timing of eating, dietary intake, obesogenic eating behaviors, and changes in appetite-regulating hormones have been identified as possible mechanisms for sleep–obesity associations and may be promising avenues for future research. Longitudinal and experimental work with children is needed to determine the nature of associations. Summary Beyond sleep duration, sleep timing patterns may contribute to obesity risk. Biological and behavioral processes have been proposed as mechanisms that may explain the association. Understanding the pathways through which poor sleep patterns could increase obesity risk in children may provide novel avenues for intervention.

Theoretical models suggest a positive relationship between sleep quality and individuals' ability to regulate emotion. However, few studies have empirically tested this hypothesized link using standardized laboratory measures of emotion-regulation ability. The present research examined the relationship between sleep quality and the ability to implement a type of emotion regulation that has particularly important implications for psychological health: cognitive reappraisal (cognitively reframing an emotional event so as to dampen its impact). To do so, 156 participants (86 male) reported on their past week's sleep quality. Their ability to implement cognitive reappraisal (CRA) was then measured with a standardized laboratory challenge. Participants with poorer self-reported sleep quality exhibited lower CRA, even after controlling for fourteen potential key confounds (e.g., age, negative affect, mood disorder symptoms, stress). This finding is consistent with the idea that poorer sleep quality may impair individuals' ability to engage in the crucial task of regulating negative emotions.

The aim of this descriptive analysis was to examine sleep timing, circadian phase, and phase angle of entrainment across adolescence in a longitudinal study design. Ninety-four adolescents participated; 38 (21 boys) were 9–10 years (“younger cohort”) and 56 (30 boys) were 15–16 years (“older cohort”) at the baseline assessment. Participants completed a baseline and then follow-up assessments approximately every six months for 2.5 years. At each assessment, participants wore a wrist actigraph for at least one week at home to measure self-selected sleep timing before salivary dim light melatonin onset (DLMO) phase – a marker of the circadian timing system – was measured in the laboratory. Weekday and weekend sleep onset and offset and weekend-weekday differences were derived from actigraphy. Phase angles were the time durations from DLMO to weekday sleep onset and offset times. Each cohort showed later sleep onset (weekend and weekday), later weekend sleep offset, and later DLMO with age. Weekday sleep offset shifted earlier with age in the younger cohort and later in the older cohort after age 17. Weekend-weekday sleep offset differences increased with age in the younger cohort and decreased in the older cohort after age 17. DLMO to sleep offset phase angle narrowed with age in the younger cohort and became broader in the older cohort. The older cohort had a wider sleep onset phase angle compared to the younger cohort; however, an age-related phase angle increase was seen in the younger cohort only. Individual differences were seen in these developmental trajectories. This descriptive study indicated that circadian phase and self-selected sleep delayed across adolescence, though school-day sleep offset advanced until no longer in high school, whereupon offset was later. Phase angle changes are described as an interaction of developmental changes in sleep regulation interacting with psychosocial factors (e.g., bedtime autonomy).