Normal sleep patterns in infants and children: A systematic review of observational studies

Children's Autonomic Nervous System Reactivity Moderates the Relations between Family Adversity and Sleep Problems in Latino 5-Year Olds in the CHAMACOS Study

Sleep problems are common for young children especially if they live in adverse home environments. Some studies investigate if young children may also be at a higher risk of sleep problems if they have a specific biological sensitivity to adversity. This paper addresses the research question, does the relations between children’s exposure to family adversities and their sleep problems differ depending on their autonomic nervous system’s sensitivity to challenges? As part of a larger cohort study of Latino, low-income families, we assessed the cross-sectional relations among family demographics (education, marital status), adversities [routines, major life events (MLE)], and biological sensitivity as measured by autonomic nervous system (ANS) reactivity associated with parent-rated sleep problems when the children were 5 years old. Mothers were interviewed in English or Spanish and completed demographic, family, and child measures. The children completed a 15-min standardized protocol while continuous cardiac measures of the ANS [respiratory sinus arrhythmia (RSA), preejection period (PEP)] were collected during resting and four challenge conditions. Reactivity was defined as the mean of the responses to the four challenge conditions minus the first resting condition. Four ANS profiles, co-activation, co-inhibition, reciprocal low RSA and PEP reactivity, and reciprocal high RSA and PEP reactivity, were created by dichotomizing the reactivity scores as high or low reactivity. Logistic regression models showed there were significant main effects for children living in families with fewer daily routines having more sleep problems than for children living in families with daily routines. There were significant interactions for children with low PEP reactivity and for children with the reciprocal, low reactivity profiles who experienced major family life events in predicting children’s sleep problems. Children who had a reciprocal, low reactivity ANS profile had more sleep problems if they also experienced MLE than children who experienced fewer MLE. These findings suggest that children who experience family adversities have different risks for developing sleep problems depending on their biological sensitivity. Interventions are needed for young Latino children that support family routines and reduce the impact of family adversities to help them develop healthy sleep practices.

A different rhythm of life: sleep patterns in the first 4 years of life and associated sociodemographic characteristics in a large Brazilian birth cohort

Objective

Sleep is an important marker of healthy development and has been associated with emotional, behavioral, and cognitive development. There is limited longitudinal data on children's sleep with only a few reports from low- and middle-income countries (LMICs). We investigate sleep parameters and associated sociodemographic characteristics in a population-based longitudinal study in Pelotas, Brazil.

Methods

Data from the Pelotas 2004 Birth Cohort were used (N = 3842). Infant sleep was collected through maternal report at 3, 12, 24, and 48 months: sleep duration, bed and wake time, nighttime awakenings, co-sleeping and sleep disturbances (24 and 48 months).

Results

Compared to children in high-income countries (HICs), children in Brazil showed a substantial shift in rhythms with later bed and wake times by approximately 2 hours. These remain stable throughout the first 4 years of life. This population also shows high levels of co-sleeping which remain stable throughout (49.0–52.2%). Later bedtime was associated with higher maternal education and family income. Higher rates of co-sleeping were seen in families with lower income and maternal education and for children who were breastfed. All other sleep parameters were broadly similar to data previously reported from HICs.

Conclusion

The shift in biological rhythms in this representative community sample of children in Brazil challenges our understanding of optimal sleep routine and recommendations.

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Biological rhythms are shifted with later bedtime by approximately 2 h (22.18 hours).

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Later bedtime is associated with higher maternal education and family income.

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High levels of co-sleeping are prevalent until 4 years of age (49% at 3 months to 52% at 4 years).

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Co-sleeping was more prevalent in families with lower income and maternal education.

Infant sleep and its relation with cognition and growth: a narrative review

OBJECTIVE

Infant sleep development is a highly dynamic process occurring in parallel to and in interaction with cognitive and physical growth. This narrative review aims to summarize and discuss recent literature and provide an overview of the relation between infant sleep and cognitive development as well as physical growth.

METHODS

We conducted online literature search using MEDLINE, Embase, and Cochrane Library databases. We considered original research on humans published in the English language from January 2005 to December 2015. Search terms included "sleep" AND "infant" AND "cognition" OR "memory" OR "executive functioning", OR "growth" OR "obesity" OR "growth hormone" OR "stunting", and combinations thereof.

RESULTS

Ten studies on infant sleep and cognition were included in this review. Overall, findings indicated a positive association between sleep, memory, language, executive function, and overall cognitive development in typically developing infants and young children. An additional 20 studies support the positive role of infant sleep in physical growth, with the current literature focusing largely on weight gain and obesity rather than healthy growth. Existing evidence in both the domains is mainly based on cross-sectional designs, on association studies, and on parental reports. In contrast, there were limited studies on longitudinal sleep trajectories and intervention effects, or studies have not used more objective sleep measures such as actigraphy and polysomnography.

CONCLUSION

The reviewed studies support a critical and positive role of infant sleep in cognition and physical growth. Future studies should consider key environmental and parental confounders, include a combination of more objective (actigraphy) and subjective measures (sleep diaries and questionnaires), and move towards longitudinal trajectory designs of infant sleep and development.

Association Between Night Waking and Child Health During the First 3 Years of Life

OBJECTIVE

Night awakening is a common concern for parents and professionals in early childhood and a risk factor for child growth and development. This study examined the concurrent and longitudinal associations of night awakening with child health and illness during the first 3 years of life.

METHODS

Longitudinal data from 1364 infants in the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development were used in this study. At ages 6, 15, 24, and 36 months, mothers reported on the frequency of their child's night awakening in the past week, overall health, and occurrences of illness. Information on demographic factors, including child sex and ethnicity/race, maternal education, and family income as well as child breastfeeding status was obtained at 1 month. Structural equation modeling, including latent growth curve modeling, was performed.

RESULTS

Age-related changes in weekly frequency of night awakening and overall child health were characterized by curvilinear patterns between 6 and 36 months. Although more frequent night awakenings were associated with poorer health at 6 months, a faster decline in night awakenings was associated with a slowed health decline over time. Furthermore, more frequent night awakenings were concurrently associated with more occurrences of illness at ages 6, 15, and 24 months. The association between night awakening and illness dissipated by 36 months.

CONCLUSION

Night awakening is concurrently and longitudinally associated with poorer health and more illnesses in early childhood.

Sleep confers a benefit for retention of statistical language learning in 6.5month old infants

Infants show robust ability to track transitional probabilities within language and can use this information to extract words from continuous speech. The degree to which infants remember these words across a delay is unknown. Given well-established benefits of sleep on long-term memory retention in adults, we examine whether sleep similarly facilitates memory in 6.5month olds. Infants listened to an artificial language for 7minutes, followed by a period of sleep or wakefulness. After a time-matched delay for sleep and wakefulness dyads, we measured retention using the head-turn-preference procedure. Infants who slept retained memory for the extracted words that was prone to interference during the test. Infants who remained awake showed no retention. Within the nap group, retention correlated with three electrophysiological measures (1) absolute theta across the brain, (2) absolute alpha across the brain, and (3) greater fronto-central slow wave activity (SWA).

Childhood Excess Weight in Spain From 2006 to 2012. Determinants and Parental Misperception

INTRODUCTION AND OBJECTIVES

Due to the high prevalence of childhood obesity in Spain, we analyzed changes in its prevalence from 2006 to 2007 and from 2011 to 2012, as well as diet, sleep, and sedentary habits in 5- to 14-year-olds and parental misperceptions about their children's excess weight.

METHODS

The sample was from the Spanish National Health Surveys for 2006 to 2007 (n=5590) and for 2011 to 2012 (n=3601). Data were collected by trained personnel through telephone interviews with parents/guardians. Weight and height were self-reported and the International Obesity Task Force cutpoints were used to define overweight and obesity.

RESULTS

The prevalence of childhood excess weight was 30.1% from 2006 to 2007 and 29.7% from 2011 to 2012, while that of childhood obesity was 9.6% and 9%, respectively. Parental misperception of childhood excess weight increased from 60.8% to 71.4% (P<.001). Daily consumption of vegetables increased by 7.8%, while that of soft drinks and snacks decreased. This decrease was greatest in children from families with a low socioeconomic status, who also decreased their consumption of sweets and fast food. Adherence to sleep recommendations decreased by 5%, but adherence to recommended sedentary time did not change.

CONCLUSIONS

High childhood overweight and obesity rates remained stable in Spain from 2006 to 2007 and from 2011 to 2012, but there was an increase in parental misperception of childhood excess weight. Despite reduced consumption of soft drinks and snacks, there was low adherence to dietary recommendations, hours of sleep, and sedentary habits.

Mandatory Nap Times and Group Napping Patterns in Child Care: An Observational Study

Policy provision for naps is typical in child care settings, but there is variability in the practices employed. One practice that might modify children's early sleep patterns is the allocation of a mandatory nap time in which all children are required to lie on their beds without alternate activity permitted. There is currently limited evidence of the effects of such practices on children's napping patterns. This study examined the association between duration of mandatory nap times and group-level napping patterns in child care settings. Observations were undertaken in a community sample of 113 preschool rooms with a scheduled nap time (N = 2,114 children). Results showed that 83.5% of child care settings implemented a mandatory nap time (range = 15-145 min) while 14.2% provided alternate activities for children throughout the nap time period. Overall, 31% of children napped during nap times. Compared to rooms with ≤ 30 min of mandatory nap time, rooms with 31-60 min and > 60 min of mandatory nap time had a two-and-a-half and fourfold increase, respectively, in the proportion of children napping. Nap onset latency did not significantly differ across groups. Among preschool children, exposure to longer mandatory nap times in child care may increase incidence of napping.

Family Income and Material Deprivation: Do They Matter for Sleep Quality and Quantity in Early Life? Evidence From a Longitudinal Study

Introduction

The aim of this article is to investigate the determinants of sleeping patterns in children up to age 9 on a large and geographically homogeneous sample of British children and parents, focusing in particular on the role of economic and social factors, specifically on income.

Aims and Methods

The data of this study come from the Avon Longitudinal Study of Parents and Children, a long-term health research project that recruited over 14000 pregnant women who were due to give birth between April 1991 and December 1992 in Bristol and its surrounding areas, including some of Somerset and Gloucestershire. Logistic regression models for the sleep problem dummies and log-linear models for the sleep quantity.

Results

One additional item in the material deprivation index is associated to an increase of around 10-20% in the odds of having at least 1 sleep problem. Similarly, children from the richest families are less likely to have any sleep problem up to 115 months (around 20% reduction in the odds). Mother's characteristics (i.e., education and mental health in the pregnancy period) are also significant predictors. Sleep quantity does not vary much and is not sensitive to socioeconomic factors.

Conclusion

Exposure to income-related inequalities affects child sleep. Further research is needed to understand if sleep in early life influences future health and economic trajectories.

Sleep differences in one-year-old children were related to obesity risks based on their parents' weight according to baseline longitudinal study data

AIM

Parental obesity is the predominant risk factor for child obesity. We compared sleep in one-year-old children with different obesity risks, based on parental weight, and explored associations with weight, parental sleep and family factors.

METHODS

Baseline data from 167 families participating in a longitudinal obesity prevention programme was used. Sleep patterns were compared between groups with high and low obesity risks, based on parental weight, and associations between child sleep and weight status, family obesity risk and parental sleep were explored. Sleep was assessed using child sleep diaries and standard parental questionnaires.

RESULTS

Later bedtime, longer sleep onset latency and lower sleep efficiency were observed among children in the high-risk group. Child sleep onset latency was associated with the family obesity risk (β = 0.25, p = 0.001), child bedtime with both maternal (β = 0.33, p < 0.01) and paternal bedtime (β = 0.22, p < 0.05) and child sleep efficiency with maternal sleep quality (β = 0.20, p < 0.01). The child's bedtime was weakly associated with their body mass index (β = 0.17, p < 0.05).

CONCLUSION

Sleep differed between one-year-old children with high or low obesity risks, based on their parents' body mass index, and was associated with the family obesity risk and parental sleep. The child's bedtime was weakly associated with their weight status.

Sleep Regulation, Physiology and Development, Sleep Duration and Patterns, and Sleep Hygiene in Infants, Toddlers, and Preschool-Age Children

Sleep problems are common, reported by a quarter of parents with children under the age of 5 years, and have been associated with poor behavior, worse school performance, and obesity, in addition to negative secondary effects on maternal and family well-being. Yet, it has been shown that pediatricians do not adequately address sleep in routine well-child visits, and underdiagnose sleep issues. Pediatricians receive little formal training in medical school or in residency regarding sleep medicine. An understanding of the physiology of sleep is critical to a pediatrician׳s ability to effectively and confidently counsel patients about sleep. The biological rhythm of sleep and waking is regulated through both circadian and homeostatic processes. Sleep also has an internal rhythmic organization, or sleep architecture, which includes sleep cycles of REM and NREM sleep. Arousal and sleep (REM and NREM) are active and complex neurophysiologic processes, involving both neural pathway activation and suppression. These physiologic processes change over the life course, especially in the first 5 years. Adequate sleep is often difficult to achieve, yet is considered very important to optimal daily function and behavior in children; thus, understanding optimal sleep duration and patterns is critical for pediatricians. There is little experimental evidence that guides sleep recommendations, rather normative data and expert recommendations. Effective counseling on child sleep must account for the child and parent factors (child temperament, parent-child interaction, and parental affect) and the environmental factors (cultural, geographic, and home environment, especially media exposure) that influence sleep. To promote health and to prevent and manage sleep problems, the American Academy of Pediatrics (AAP) recommends that parents start promoting good sleep hygiene, with a sleep-promoting environment and a bedtime routine in infancy, and throughout childhood. Thus, counseling families on sleep requires an understanding of sleep regulation, physiology, developmental patterns, optimal sleep duration recommendations, and the many factors that influence sleep and sleep hygiene.

Interactions between sleep, movement and other non-movement behaviours in the pathogenesis of childhood obesity

Research examining the health effects of physical activity, sedentary behaviour and sleep on different health outcomes has largely been conducted independently or in isolation of the other behaviours. However, the fact that time is finite (i.e. 24 h) suggests that the debate on whether or not the influence of a single behaviour is independent of another one is conceptually incorrect. Time spent in one behaviour should naturally depend on the composition of the rest of the day. Recent evidence using more appropriate analytical approaches to deal with this methodological issue shows that the combination of sleep, movement and non-movement behaviours matters and all components of the 24-h movement continuum should be targeted to enhance health and prevent childhood obesity. The objective of this review is to discuss research investigating how combinations of physical activity, sedentary behaviour and sleep are related to childhood obesity. Emerging statistical approaches (e.g. compositional data analysis) that can provide a good understanding of the best 'cocktail' of behaviours associated with lower adiposity and improved health are also discussed. Finally, future research directions are provided. Collectively, it becomes clearer that guidelines and public health interventions should target all movement behaviours synergistically to optimize health of children and youth around the world.

Words to Sleep On: Naps Facilitate Verb Generalization in Habitually and Nonhabitually Napping Preschoolers

A nap soon after encoding leads to better learning in infancy. However, whether napping plays the same role in preschoolers' learning is unclear. In Experiment 1 (N = 39), 3-year-old habitual and nonhabitual nappers learned novel verbs before a nap or a period of wakefulness and received a generalization test examining word extension to novel actors after 24 hr. Only habitual and nonhabitual nappers who napped after learning generalized 24 hr later. In Experiment 2 (N = 40), children learned the same verbs but were tested within 2-3 min of training. Here, habitual and nonhabitual nappers retained the mappings but did not generalize. The results suggest that naps consolidate weak learning that habitual and nonhabitual nappers would otherwise forget over periods of wakefulness.

Impact of different recommendations on adequacy rate for sleep duration in children

A huge amount of literature in the last decades showed that sleep is essential for children’s health and well-being and that short sleep duration is associated with several negative health outcomes. Many developmental phases in infancy and childhood are in strict relationship with an healthy sleep.

In the last years some specific recommendations made for how much sleep children need have been published. The empirical evidences for contemporary sleep recommendations has changed and the new recommendations are clearly different from the previous ones and reflect clearly the changes in the sleep need of the children and adolescents in the last decades although seem still to be largely unfitting for preadolescence and adolescence.

If sleep is to be treated as a therapeutic intervention, then consensus guidelines, statements, and evidence-based best-practice documents are needed to underpin sleep recommendations for children.

Sleep recommendations for children play an important role for public policies and interventions, and to advertise parents and children of the negative consequences of sleep deprivation/reduction.

Six-month-old infant long sleepers prefer a human face

BACKGROUND

Sleep is known to influence socio-emotional regulation among children and preschoolers, whereas little is known about the association between sleep and social preference during infancy.

METHODS

In the current study, habitual sleep of 49 infants aged around six months old were surveyed by questionnaire, and their social preference was revealed by their preferential gaze in three conditions: (1) a human face paired with an object (ie, a cup), (2) a human face paired with an animal face (ie, a dog), and (3) a dog face paired with a cup.

RESULTS

In general, images with richer social information (ie, a human face and dog) attracted infants' gaze significantly more than nonsocial images (ie, cup). Infants with shorter sleep duration (ie, <13 h a day) show a significant reduction in their preference toward a human face when paired with a dog than infants with longer sleep duration.

CONCLUSIONS

Our findings suggest an early positive link between sleep duration and preference towards socially rich stimuli (eg, a human face) during infancy.

Maternal depressed mood moderates the impact of infant sleep on mother-infant bonding

Parent-infant bonding has long-term consequences for the psychological wellbeing of the child. Considering the centrality of infant sleep patterns in infant-caregiver interactions in the first year of life, we propose that infant sleep patterns act as a catalyst or disruptor for mother-infant relationship, such that infant sleep patterns contribute to maternal mood, maternal sleep quality, perception of infant temperament, and her bonding experience. One hundred fifty-two Israeli mothers, of 5-8-month-old infants, responded to Internet-based questionnaires regarding their sleep, their mood, their infant's sleep, the infant's temperament, and their bonding experience. Eight percent of the mothers reported clinically significant depression, while 67 % reported significant sleep difficulties. Infant sleep difficulties correlated with maternal mood and sleep quality, infant fussiness, and bonding. Structural equation modeling demonstrated that maternal sleep partially mediated the relationship between infant sleep and maternal mood. Additionally, 22 % of the variance in bonding was explained by infant sleep problems and temperament. Notably, maternal depression moderated this effect such that infant sleep problems correlated with bonding only in those mothers who were depressed. The results suggest that infant sleep is a vector by which maternal cognitions and mood are transmitted to her child, with long-term implications for psychological development.

Developmental Trajectories of Sleep Problems from Childhood to Adolescence Both Predict and Are Predicted by Emotional and Behavioral Problems

Although the prevalence rates of sleep disorders at different stages of childhood and adolescence have been well established, little is known about the developmental course of general sleep problems. This also holds true for the bidirectional relationship between sleep problems and emotional as well as behavioral difficulties. This longitudinal study investigated the general pattern and the latent trajectory classes of general sleep problems from a large community sample aged 5–14 years. In addition, this study examined the predictive value of emotional/behavioral difficulties (i.e., anxiety/depression, attention problems, and aggressive behavior) on sleep problems latent trajectory classes, and vice-versa. Participants (N = 1993) were drawn from a birth cohort of Western Australian children born between 1989 and 1991 who were followed until 14 years of age. Sleep problems were assessed at ages 5, 8, 10, and 14, respectively, whereas anxiety/depression, attention problems, and aggressive behavior were assessed at ages 5 and 17 years. Latent growth curve modeling revealed a decline in an overall pattern of sleep problems during the observed 10-year period. Anxiety/depression was the only baseline factor that predicted the longitudinal course of sleep problems from ages 5 to 14 years, with anxious and depressed participants showing faster decreasing patterns of sleep problems over time than those without anxiety or depression. Growth mixture modeling identified two classes of sleep problem trajectories: Normal Sleepers (89.4%) and Troubled Sleepers (10.6%). Gender was randomly distributed between these groups. Childhood attention problems, aggressive behavior, and the interaction between gender and anxiety/depression were significantly predictive of membership in the group of Troubled Sleepers. Group membership in Troubled Sleepers was associated with higher probability of having attention problems and aggressive behavior in mid-adolescence. Boys and girls with behavioral difficulties, and girls with emotional difficulties were at increased risk of having sleep problems during later childhood and adolescence. Developmental trajectories of sleep problems were also predictive of behavioral difficulties in later life. Findings from this study provide empirical evidence for the heterogeneity of sleep problems and their development, and emphasize the importance of understanding sleep problems and their relationship to children and adolescents’ mental health.

Understanding the Relationship Between Asthma and Sleep in the Pediatric Population

The Centers for Disease Control and Prevention reports that 9.5% of children have been diagnosed with asthma. Sleep disturbances affect 20% to 30% of the pediatric population. The prevalence of nocturnal symptoms of asthma is high, and most children regularly experience nighttime symptoms. Sleep is important for growth and development, and untreated sleep disturbances have adverse effects on school performance, mental health, physical health, and functioning. This review will explore the relationship between asthma and sleep disturbances. Clinicians need to assess children with asthma for sleep disturbance.

Exploring Maternal Perceptions of Infant Sleep and Feeding Method Among Mothers in the United Kingdom: A Qualitative Focus Group Study

BACKGROUND

In a context with strong rhetorical support for breastfeeding in the health system, yet extremely low rates of breastfeeding after hospital discharge, U.K. women's decisions about infant feeding reflect the reality of competing priorities in their lives, including obtaining adequate sleep. Popular wisdom in the U.K. tightly links breastfeeding and inadequate night-time sleep. Mothers are advised by peers and family to introduce formula or solid foods to infants to promote longer sleep.

OBJECTIVES

The first objective of this study was to investigate women's understandings of the nature of infant sleep and their perceptions of links between infant feeding method and sleep. The second was to explore how these perceptions influence infant feeding and sleep practices. Underpinning our work is the understanding that infant care choices result from trade-offs by which mothers strive to balance infant- and self-care.

METHODS

We conducted seven focus groups with mothers of infants in two regions of the U.K. Verbatim transcripts were thematically coded and emergent themes were identified.

RESULTS

We found clearly diverging narratives between breastfeeding and formula-feeding mothers. Breastfeeding mothers viewed the fragmentary nature of infant sleep as natural, while mothers who were formula feeding felt this was a problem to be fixed.

CONCLUSIONS AND PRACTICE

The strategies used to promote infant and maternal sleep in each group were aligned with their underlying perception of how infant sleep works. Maternal perceptions of the nature of infant sleep and its relation to infant feeding method impact infant care practices in the first year of life.

Racial/Ethnic and Socio-Contextual Correlates of Chronic Sleep Curtailment in Childhood

STUDY OBJECTIVES

To examine the association between race/ethnicity and sleep curtailment from infancy to mid-childhood, and to determine the extent to which socioeconomic and contextual factors both explain racial/ethnic differences and are independently associated with sleep curtailment.

METHODS

We studied 1,288 children longitudinally in Project Viva, a pre-birth cohort study, from 6 months to 7 years of age. The main exposure was the child's race/ethnicity. The main outcome was a sleep curtailment score from 6 months to 7 years. The score ranged from 0-13, where 0 indicated maximal sleep curtailment and 13 indicated never having curtailed sleep.

RESULTS

The mean (standard deviation) sleep curtailment score was 10.2 (2.7) points. In adjusted models (β [95% CI]), black (-1.92, [-2.39, -1.45] points), Hispanic (-1.58, [-2.43, -0.72] points), and Asian (-1.71, [-2.55, -0.86] points) children had lower sleep scores than white children. Adjustment for sociodemographic covariates attenuated racial/ethnic differences in sleep scores for black (by 24%) and Hispanic children (by 32%) but strengthened the differences for Asian children by 14%. Further adjustment for environmental and behavioral variables did not substantially change these differences. Independently, low maternal education, living in households with incomes < $70,000, viewing more TV, and having a TV in the child's bedroom were associated with lower sleep scores.

CONCLUSIONS

Chronic sleep curtailment from infancy to mid-childhood was more prevalent among black, Hispanic, and Asian children. These differences were partially but not entirely explained by socio-contextual variables. Independently, children from lower socioeconomic status and those with greater exposures to TV also had greater sleep curtailment.

Actigraphic motor activity during sleep from infancy to adulthood

A secondary analysis of longitudinal and cohort studies was carried out to quantitatively investigate the motor activity pattern, recorded through actigraphy, during the first six hours of nocturnal sleep. The first study was of longitudinal nature. Ten healthy participants (four females) were monitored three times, at baseline (T1) when they were infants (mean age 7.10 ± 0.32 months), at the first follow-up examination (T2) around 4 months later (mean age 11.20 ± 0.63 months) and at the second follow-up (T3) around three years later, when they were preschoolers (mean age 4.68 ± 0.14 years). At T1, T2 and T3 each participant wore the actigraph Basic Mini-Motionlogger (Ambulatory Monitoring, Inc., Ardsley, NY, USA) over at least two consecutive nycthemeral cycles, with the aim to measure the mean hourly motor activity count. Seven- and 11-month-old infants had a higher level of motor activity over the night compared to preschoolers. Furthermore, motor activity increased as the night progressed, with a pronounced increment at both T1 and T2, while at T3 such an increase was less marked. The second study was cross-sectional and aimed to explore the motor activity pattern, using actigraphy, during the first six hours of nocturnal sleep in multiple-age healthy groups, from infancy to adulthood. We assigned participants to eight groups according to age: 20 (five females) aged around 10 months old (mean age 10.65 ± 0.67 months); 13 (nine females) aged around 4 years (mean age 4.38 ± 0.51 years); 21 (10 females) aged around 10 years (mean age 9.67 ± 0.91 years); 21 (nine females) aged around 20 years (mean age 19.33 ± 2.44 years); 20 (10 females) aged around 30 years (mean age 29.80 ± 1.99 years); 20 (15 females) aged around 40 years (mean age 40.70 ± 1.26 years); 20 (11 females) aged around 50 years (mean age 50.15 ± 2.80 years) and 20 (nine females) aged around 60 years (mean age 59.25 ± 3.23 years). The participants aged between 10 and 60 years wore the actigraph Basic Mini-Motionlogger over seven consecutive nycthemeral cycles (infants and preschoolers wore the actigraph over at least two consecutive nycthemeral cycles), with the aim to measure the mean hourly motor activity count. The results indicated a significantly higher motor activity count in 10-month-old infants compared to all the remaining age groups. Moreover, the pattern of motor activity of 10-month-old infants was different from that of all other groups, with the highest motor activity counts from the second to the sixth hour of sleep. Considered as a whole, the results of both studies converge regarding the high motor activity detected among infants, which could be explained by the presence of a maturational process that has not yet been fully completed at this stage of life. In both studies, only the motor activity of infants was above the cutoff level established for normal adults, highlighting the need to establish a specific cutoff value for infants.

The Effect of Sleep on Children's Word Retention and Generalization

In the first few years of life children spend a good proportion of time sleeping as well as acquiring the meanings of hundreds of words. There is now ample evidence of the effects of sleep on memory in adults and the number of studies demonstrating the effects of napping and nocturnal sleep in children is also mounting. In particular, sleep appears to benefit children's memory for recently-encountered novel words. The effect of sleep on children's generalization of novel words across multiple items, however, is less clear. Given that sleep is polyphasic in the early years, made up of multiple episodes, and children's word learning is gradual and strengthened slowly over time, it is highly plausible that sleep is a strong candidate in supporting children's memory for novel words. Importantly, it appears that when children sleep shortly after exposure to novel word-object pairs retention is better than if sleep is delayed, suggesting that napping plays a vital role in long-term word retention for young children. Word learning is a complex, challenging, and important part of development, thus the role that sleep plays in children's retention of novel words is worthy of attention. As such, ensuring children get sufficient good quality sleep and regular opportunities to nap may be critical for language acquisition.

Influence of asthma status on sleep variability in overweight/obese youth

OBJECTIVE

Pediatric asthma and overweight/obesity (OV/OB) frequently co-occur and youth with both conditions exhibit poor sleep/bedtime habits. This study assessed differences in week-to-weekend bedtime/wake time variability among OV/OB youth with/without comorbid asthma, and tested whether variability predicted weekday sleep.

METHODS

OV/OB youth (n = 142; 28% comorbid asthma; 7-12 years) wore an Accelerometer for 5 days (2 weekend days), providing estimates of week-to-weekend bedtime/wake-time variability, weekday Total Sleep Time (TST), weekday time in bed (TIB), and weekday wake after sleep onset (WASO).

RESULTS

There were no demographic differences between groups beyond lower family income for the OV/OB+asthma group. The OV/OB+asthma group exhibited later weekday (mean OV/OB+asthma = 10:39 pm, mean OV/OB only = 10:30pm) and weekend (mean OV/OB+asthma = 11:41 pm, mean OV/OB only = 11:17pm) bedtimes, earlier weekday waketimes (mean OV/OB+asthma = 6:40 am, mean OV/OB only = 6:51 am), and similar weekend waketimes (mean OV/OB+asthma = 7:54 pm, mean OV/OB only = 7:52 pm. Univariate MANOVA follow-ups indicated a main effect of asthma group for week-to-weekend bedtime and waketime variability, with the OV/OB+asthma group evidencing approximately 30 minutes greater bedtime (OV/OB+asthma mean = 90 minutes) and waketime (OV/OB+asthma mean = 108 minutes) variability. Within the OV/OB+asthma group, greater waketime variability predicted fewer minutes of weekday TIB and WASO. Within the OV/OB only group, wake time variability predicted fewer minutes of weekday TIB.

CONCLUSION

Findings suggest that asthma status confers risk for more week-to-weekend variability among currently OV/OB youth, and that greater variability shortens the weekday sleep period. Further research on reasons for greater week-to-weekend sleep variability in asthma is needed.

Fifteen-minute consultation on problems in the healthy child: sleep

Sleep-related issues are common reasons children present to health professionals. Many factors can adversely affect sleep quality, and there are many associations of inadequate sleep, including behavioural problems, obesity and accidental injury. We review the current evidence, and suggest practical management strategies to promote better sleep, and hopefully, better functioning for child and family alike.

Intraindividual variability of sleep/wake patterns in relation to child and adolescent functioning: A systematic review

Substantial research attention has been devoted to understanding the importance and impact of sleep in children and adolescents. Traditionally, this has focused on mean sleep variables (e.g., a child's "typical" or average sleep duration), yet research increasingly suggests that intraindividual variability (IIV) of sleep/wake patterns (sometimes referred to as sleep variability or night-to-night variability) regularly occurs and may have implications for adjustment. A systematic search of five electronic databases identified 52 empirical studies published between 2000 and 2015 that examined correlates of sleep IIV in children and adolescents, with a recent increase in the publication rate of such studies. Identified studies were often atheoretical and included post hoc analyses, though IIV in select aspects of sleep does appear to be associated with increasing age/pubertal status, non-White race, physical and neurodevelopmental conditions (e.g., attention-deficit/hyperactivity disorder; autism), psychopathology symptoms (e.g., anxiety, depression, inattention), body weight, stress, aspects of cognitive functioning, and poorer sleep functioning/habits. The limited intervention work examining sleep IIV in adolescents is promising, though studies are needed using more rigorous intervention designs. Clinical sleep recommendations may not only need to address overall sleep duration and sleep habits but also the stability of sleep duration and timing. It will be important for future research examining sleep IIV in children and adolescents to use a developmental framework in advancing theory pertaining to the causes, mechanisms, moderators, and outcomes of sleep IIV in youth, and a conceptual model is proposed to help guide such efforts.

Infant sleep-wake behaviors at two weeks, three and six months

Although infant sleep-wake behavior presents several developmental changes during the first six months, literature lacks on reference values and few studies have explored the role of individual change and stability on infant sleep-wake behavior during the first six months. This study aimed (1) to describe infant sleep-wake behaviors during the 24-h period, day and night, at two weeks, three, and six months, (2) and to explore developmental changes and the role of individual change and stability on infant sleep-wake behaviors from two weeks to six months. Ninety-four primiparous mothers completed measures on infant sleep-wake behaviors at two weeks, three and six months. Significant developmental changes were found on infant sleep-wake behaviors from two weeks to six months. Two-week-old infants sleep 13.3h, spend 8.7h awake, awake 6.1 times, have 0.4h of latency to sleep, and 3.2h of longest sleep period. Three-month-old infants sleep 13.0h, spend 9.2h awake, awake 5.5 times, have 0.4h of latency to sleep, and 5.2h of longest sleep period. Six-month-old infants sleep 12.2h, spend 10.0h awake, awake 5.2 times, have 0.4h of latency to sleep, and 5.6h of longest sleep period. Significant individual change and stability were also found on infant sleep-wake behaviors from two weeks to six months. Despite significant developmental and individual changes, individual stability explains a significant amount of the variance on infant sleep-wake behaviors over the first six months of life.

Sleep-patterns, co-sleeping and parent's perception of sleep among school children: Comparison of domicile and gender

This study was aimed at assessment of sleep schedule, pre-sleep behavior, co-sleeping and parent's perception of sleep of school going children.

METHOD

Four schools each, from urban and rural area were included. Sleep patterns were assessed using the validated Hindi version of Childhood-Sleep-Habit-Questionnaire. Comparison was made between urban and rural group and between boys and girls. Interaction of gender, domicile and school-type was examined on the sleep patterns.

RESULTS

This study included 831 school children with mean age of 8.9 years. Nearly half of the subjects were boys in this study. Urban children outnumbered those from rural area. Total sleep time on weekdays was 8.3 h that increased to 9.5 h on weekends. Rural children spent more time in sleep than urban children on weekdays and weekends. A higher proportion of urban children felt sleepy during the day. Television watching before bedtime was more common in urban settings. Room sharing was more common among rural children. Nearly 65% rural parents as compared to 77.5% urban parents reported that their child was sleeping sufficient enough. Gender did not affect sleep-schedule and parent's perception regarding their child's sleep. Interaction between gender, domicile and school-type did not have any significant effect on sleep patterns.

CONCLUSION

Television watching before bedtime was more common among urban school children and they had shorter total sleep time. They had signs of sleep deprivation. Room sharing was more common among rural children. Despite longer sleep time, parents of rural children felt the need for more sleep.

Putting Children's Sleep Problems to Bed: Using Behavior Change Theory to Increase the Success of Children's Sleep Education Programs and Contribute to Healthy Development

Sleep is critical for the healthy development of children, yet most children simply don’t get enough. Whilst school based sleep education programs have been developed for parents and their children, they have had mixed success. We consider how existing school-based sleep education programs can be improved by applying a broader model to behaviour change theory. We find that the mixed success of school-based sleep education programs may be due to a plausible but misleading assumption that simply increasing information about the importance of sleep and the risks of insufficient and/or inefficient sleep, will necessarily result in improved sleep behaviours. We identify the potential benefits of using a more inclusive behavior change theory in the development of sleep education programs with a particular need for theories that incorporate the multiple biological, environmental and social impacts on children’s sleep. Bronfenbrenner’s Bioecological model is presented to illustrate how one such inclusive behavior change theory could significantly improve the success of sleep education programs and ultimately support the healthy development of children.

Associations between bedtime and nighttime parenting and infant cortisol in the first year

We examined how maternal care within the bedtime and nighttime contexts influences infant cortisol levels and patterning. Eighty-two mothers (M_age  = 29.4 years) and infants participated in a longitudinal study when infants were 3, 6, and 9 months old. At each time point, bedtime and nighttime parenting were recorded and infant cortisol at bedtime and the following morning was analyzed. Multilevel model analyses showed that infants had lower cortisol levels when mothers were more emotionally available at bedtime, and infants whose mothers responded more often to their non-distressed cues had lower cortisol levels on average. Less co-sleeping and more maternal responses to infant distress were linked to healthier cortisol patterning. By shedding light on parenting qualities and behaviors that influence infant cortisol, these results indicate avenues for intervention and suggest the utility of studying parenting in infant sleep contexts.

Sleep Patterns, Sleep Disturbances, and Associated Factors Among Chinese Urban Kindergarten Children

This study aimed to characterize sleep patterns and disturbances among Chinese urban kindergarten children and examine potentially associated factors. Caregivers of 513 children (47.96% male) aged 3-6 years (mean age = 4.46, SD = 0.9) completed the Children's Sleep Habits Questionnaire (CSHQ) and the Strengths and Difficulties Questionnaire (SDQ). Almost 80% (78.8%) of the children scored above the original CSHQ cutoff point for global sleep disturbance. Regression analysis indicated that child's age, and the presence of emotional problems, hyperactivity and peer problems, cosleeping, and interparental inconsistency of attitudes toward child rearing accounted for significant variance in the CSHQ total score (R(2) = 22%). These findings indicate that there is an apparently high prevalence of sleep disturbances in Chinese urban kindergarten children; and sleep disturbances are associated with both child-related and parenting practice variables.

Determinants of sleep disturbances in Rett syndrome: Novel findings in relation to genotype

Rett syndrome is a rare but severe neurological disorder associated with a mutation in the methyl CpG binding protein 2 (MECP2) gene. Sleep problems and epilepsy are two of many comorbidities associated with this disorder. This study investigated the prevalence and determinants of sleep problems in Rett syndrome using an international sample. Families with a child with a confirmed Rett syndrome diagnosis and a MECP2 mutation registered in the International Rett Syndrome Phenotype Database (InterRett) were invited to participate. Questionnaires were returned by 364/461 (78.9%) either in web-based or paper format. Families completed the Sleep Disturbance Scale for Children and provided information on the presence, nature, and frequency of their child's sleep problems. Multivariate multinomial regression was used to investigate the relationships between selected sleep problems, age group, and genotype and linear regression for the relationships between sleep disturbance scales and a range of covariates. Night waking was the most prevalent sleep problem affecting over 80% with nearly half (48.3%) currently waking often at night. Initiating and maintaining sleep was most disturbed for younger children and those with a p.Arg294* mutation. Severe seizure activity was associated with poor sleep after adjusting for age group, mutation type, and mobility. We were surprised to find associations between the p.Arg294* mutation and some sleep disturbances given that other aspects of its phenotype are milder. These findings highlight the complexities of aberrant MECP2 function in Rett syndrome and explain some of the variation in manifestation of sleep disturbances. © 2016 Wiley Periodicals, Inc.

Treating Obesity in Preschoolers: A Review and Recommendations for Addressing Critical Gaps

Developing interventions targeting obesity reduction in preschoolers is an emergent area. Although intensive, multicomponent interventions seem a promising approach to preschool obesity reduction, this review identifies and discusses approaches to 3 critical gaps (poor reach to families from low-income and minority backgrounds, lack of sufficient evidence to determine the most effective and efficient treatment components and approaches to treating obesity in early childhood, and lack of consensus on how best to discern intervention effectiveness) that need to be addressed to advance the preschool obesity literature.

An update to the Greig Health Record: Executive summary

The Greig Health Record is an evidence-based health promotion guide for clinicians caring for children and adolescents 6 to 17 years of age. It provides a template for periodic health visits that is easy to use and adaptable for electronic medical records. On the record, the strength of recommendations is indicated in boldface for good, in italics for fair, and in regular typeface for recommendations based on consensus or inconclusive evidence. Checklist templates include sections for Weight, Height and BMI, Psychosocial history and Development, Nutrition, Education and Advice, Specific Concerns, Examination, Assessment, Immunization, and Medications. Included with the checklist tables are five pages of selected guidelines and resources. This update includes information from recent guidelines and research in preventive care for children and adolescents 6 to 17 years of age. Regular updates are planned. The complete Greig Health Record can be found online at the Canadian Paediatric Society's website: www.cps.ca.

Bidirectional associations between bedtime parenting and infant sleep: Parenting quality, parenting practices, and their interaction

In keeping with transactional conceptualizations of infant sleep development (Sadeh, Tikotzky, & Scher, 2010), the present study was an examination of longitudinal, bidirectional linkages between bedtime parenting (through direct observations of parenting practices and quality) and infant sleep across the first 6 months postpartum. In doing so, we also drew from Darling and Steinberg's (1993) conceptual model to examine parenting quality as a moderator of linkages between specific bedtime practices and infant sleep. Multilevel model analyses revealed that the strongest increases in infant nighttime sleep across the first 6 months occurred among infants of mothers who engaged in low levels of nursing at bedtime. Within-person linkages between mothers' emotional availability (EA) at bedtime, infant distress, and infant sleep were found, such that at time points when mothers were more emotionally available, infants were less distressed and slept more throughout the night. Several moderating effects of maternal EA on linkages between parenting practices and infant sleep were obtained that were consistent with predictions from Darling and Steinberg (1993). Higher maternal EA in combination with less close contact at bedtime was associated with more infant sleep across the night on average, and higher EA in combination with fewer arousing bedtime activities predicted more rapid increases in infant sleep with age. Finally, there was evidence of infant-driven effects, as higher infant nighttime distress predicted lower EA at subsequent time points. Results showcased the complex, reciprocal interplay between parents and infants in the development of infant sleep patterns and parenting behavior during the first 6 months postpartum. (PsycINFO Database Record

[A prospective study of the development of nocturnal sleep patterns in infants]

OBJECTIVE

To investigate the development of nocturnal sleep pattern in infants.

METHODS

Fifty healthy full-term newborns born in Chongqing Maternal and Child Health Care Hospital were chosen for a prospective longitudinal study. A non-invasive sleep monitor, Actiwatch, was used to monitor infants' 12 sleep parameters on the 10th day, 28th day, the first Tuesday at the 2nd, 3rd, 4th, 5th, 6th, 9th and 12th month after birth, each monitoring time lasting 60 hours. All sleep parameters were analyzed by two-level mixed effect model.

RESULTS

Twenty-two boys and 25 girls completed the whole follow-up study. From birth to the 12th month after birth, the nocturnal sleep onset latency (NSOL) decreased by about 48% at 3 months of age and by 83% at 6 months of age. The nocturnal sleep efficiency (NSE%) increased from 66% to 87%, the nocturnal total sleep time (NTST) increased from 416 minutes to 517 minutes, and the longest nocturnal continuous sleeping time (L-NCST) increased from 197 minutes to 327 minutes. NSE%, NTST and L-NCST increased with age (P<0.01). The 3rd to 12th month ratios of NSE%, NTST and L-NCST were 86%, 84% and 72%, respectively, and the 6th to 12th month ratios of those were 97%, 91% and 94%, respectively. The nocturnal total wake time (NTWT) and longest nocturnal continuous waking times (L-NCWT) decreased with age (P<0.01). The decline speeds in the first half year were 5-6 times of those in the second half year after birth (P<0.05). NTST, nocturnal continuous sleeping ability and NSE% in boys were lower than those in girls (P<0.05).

CONCLUSIONS

Infantile nocturnal sleep patterns develop rapidly during the first 6 months, especially within the first 3 months after birth. Partial infantile sleep parameters are related to gender.

Associations of outdoor play and screen time with nocturnal sleep duration and pattern among young children

AIM

Sleep duration and pattern have important implications for children's health. This study aims to investigate nocturnal sleep duration, sleep pattern and their relationships with outdoor play and screen time among children aged 2 to five years.

METHODS

The study used data from the Healthy Beginnings Trial undertaken in Sydney, Australia. Data on children's sleep, outdoor playtime and screen time were reported by mothers via face-to-face interviews when children were 2, 3.5 and five years old. Both cross-sectional and longitudinal analyses were conducted.

RESULTS

At age 2, 3.5 and five years, 497, 415 and 369 mother-child dyads participated. Significantly, there was an overall increase in children's nocturnal sleep duration, sleep latency and an earlier bedtime, and there was a decrease in the proportion of children who woke at night over time. Each additional hour of screen time was associated with three-minute (95% CI 0.6-5) shorter sleep, 1.6-minute (95% CI 0.59-2.63) longer sleep latency, four-minute (95% CI 1.8-6.0) later bedtime and less likely sleeping ≥10 hours per night with adjusted odds ratio 0.88 (95% CI 0.77-1.00), after controlling for mothers' demographics.

CONCLUSION

Among young children, screen time and outdoor playtime were associated with sleep duration and pattern. Reducing screen time and increasing outdoor playtime might help improving children's sleep.

Annual Research Review: Sleep problems in childhood psychiatric disorders--a review of the latest science

BACKGROUND

Hippocrates flagged the value of sleep for good health. Nonetheless, historically, researchers with an interest in developmental psychopathology have largely ignored a possible role for atypical sleep. Recently, however, there has been a surge of interest in this area, perhaps reflecting increased evidence that disturbed or insufficient sleep can result in poor functioning in numerous domains. This review outlines what is known about sleep in the psychiatric diagnoses most relevant to children and for which associations with sleep are beginning to be understood. While based on a comprehensive survey of the literature, the focus of the current review is on the latest science (largely from 2010). There is a description of both concurrent and longitudinal links as well as possible mechanisms underlying associations. Preliminary treatment research is also considered which suggests that treating sleep difficulties may result in improvements in behavioural areas beyond sleep quality.

FINDINGS

To maximise progress in this field, there now needs to be: (a) greater attention to the assessment of sleep in children; (b) sleep research on a wider range of psychiatric disorders; (c) a greater focus on and examination of mechanisms underlying associations; (d) a clearer consideration of developmental questions and (e) large-scale well-designed treatment studies.

CONCLUSIONS

While sleep problems may sometimes be missed by parents and healthcare providers; hence constituting a hidden risk for other psychopathologies - knowing about these difficulties creates unique opportunities. The current excitement in this field from experts in diverse areas including developmental psychology, clinical psychology, genetics and neuropsychology should make these opportunities a reality.

Feeding methods, sleep arrangement, and infant sleep patterns: a Chinese population-based study

BACKGROUND

Findings from prior research into the effect of feeding methods on infant sleep are inconsistent. The objectives of this study were to examine infants' sleep patterns by feeding methods and sleep arrangement from birth to eight months old.

METHODS

This longitudinal cohort study enrolled 524 pregnant women at 34-41 weeks of gestation and their infants after delivery in 2006 and followed up until eight months postpartum. The study subjects were recruited from nine women and children hospitals in nine cities in China (Beijing, Chongqing, Wuhan, Changsha, Nanning, Xiamen, Xi'an, Jinan, and Hailin). Participating infants were followed up weekly during the first month and monthly from the second to the eighth month after birth. Twenty-four hour sleep diaries recording infants' sleeping and feeding methods were administered based on caregiver's self-report. Multivariable mixed growth curve models were fitted to estimate the effects of feeding methods and sleep arrangement on infants' sleep patterns over time, controlling for maternal and paternal age, maternal and paternal education level, household income, supplementation of complementary food, and infant birth weight and length.

RESULTS

Exclusively formula fed infants had the greatest sleep percentage/24 h, followed by exclusively breast milk fed infants and partially breast milk fed infants (P<0.01). Night waking followed a similar pattern. However, the differences in sleep percentage and night waking frequency between exclusively formula and exclusively breast milk fed infants weakened over time as infants developed. In addition, compared to infants with bed-sharing sleep arrangement, those with room sharing sleep arrangement had greater daytime and 24-hour infant sleep percentage, whereas those with sleeping alone sleep arrangement had greater nighttime sleep percentage.

CONCLUSIONS

Our data based on caregiver's self-report suggested that partial breastfeeding and bed-sharing may be associated with less sleep in infants. Health care professionals need to work with parents of newborns to develop coping strategies that will help prevent early weaning of breastfeeding.

Behavioral Management of Sleep Problems in Infants Under 6 Months--What Works?

OBJECTIVE

Crying and unsettled behavior in infancy is common. Prolonged disturbed infant sleep can have significant negative effects on the development of the child, and on the psychological well-being of the mother. Compared to studies examining the effects of behavioral sleep programs such as extinction-based techniques in infants over 6 months of age, fewer studies have looked at such strategies in infants under 6 months of age. The aim of this article is to summarize the literature examining the effects of behavioral techniques on infant sleep outcomes in the first 6 months of life and provide evidence based recommendations for the management of infant sleep disturbance.

METHOD

An electronic search of the literature was performed to identify studies which examined the effects of a behavioral intervention aimed at improving sleep in infants under 6 months of age.

RESULTS

Eleven studies were identified, of which 8 demonstrated improvements in infant sleep outcomes subsequent to the implementation of an educational behavioral program.

CONCLUSION

Education directed to parents about the use of simple, prescriptive, behavioral techniques is effective in improving infant sleep. Long term follow-up studies have failed to find any negative effects on the child, either from a psychological or physical perspective.

Less Efficient Neural Processing Related to Irregular Sleep and Less Sustained Attention in Toddlers

The current study used event-related potentials to examine a candidate process through which sleep difficulties affect attentional processing in toddlers. Fifteen toddlers participated in an auditory Oddball task while neurophysiological data were collected. Sleep deficits were assessed using actigraphs, and attention was examined with a sustained attention task. A P3-like component was elicited from the toddlers, and longer target P3 latencies were associated with poorer sustained attention and irregular sleep. Findings suggest that irregular sleep is associated with less efficient attentional processing as reflected by the P3 component, and that longer target P3 latencies are associated with poorer sustained attention.

Temporal Associations Between Sleep and Physical Activity Among Overweight/Obese Youth

OBJECTIVE

Examine average interindividual and temporal intraindividual associations between time of sleep onset (sleep onset), total sleep time (TST), and minutes in moderate-to-very-vigorous physical activity per hour (MVPA/h) among overweight/obese youth.

METHODS

Overweight/obese youth (n = 134; 7-12 years) wore an accelerometer for 16+ hr/day, 5-7 days, which provided daily objective estimates of MVPA/h, TST, and sleep onset.

RESULTS

Multilevel models revealed an intraindividual effect of TST, such that nights with longer TST preceded less MVPA/h during the midnight-to-midnight monitoring period; a significant random effect qualified this relationship. Average interindividual TST did not predict mean MVPA/h, whereas sleep onset significantly predicted mean MVPA/h.

CONCLUSIONS

Later time of sleep onset (as opposed to TST) was the strongest predictor of group-level decreased physical activity. At the individual level, longer TST than usual predicted less MVPA/h than usual. Results suggest the need for more person-centered research and a greater focus on sleep timing among youth.

The relationship between prior night's sleep and measures of infant imitation

We examined whether sleep quality during the night and naps during the day preceding a learning event are related to memory encoding in human infants. Twenty-four 6- and twenty-four 12-month-old infants' natural sleeping behavior was monitored for 24 hr using actigraphy. After the recording period, encoding was assessed using an imitation paradigm. In an initial baseline phase, infants were allowed to interact with the stimulus to assess spontaneous production of any target actions. Infants then watched an experimenter demonstrate a sequence of three target actions and were immediately given the opportunity to reproduce the demonstrated target actions to assess memory encoding. Analyses revealed significant correlations between nighttime sleep quality variables (sleep efficiency, sleep fragmentation) and immediate imitation in 6-month-olds, but not in 12-month-olds. High sleep quality in the preceding night was thus positively associated with next day's memory encoding in 6-month-old infants.

Start Later, Sleep Later: School Start Times and Adolescent Sleep in Homeschool Versus Public/Private School Students

Homeschooled students provide a naturalistic comparison group for later/flexible school start times. This study compared sleep patterns and sleep hygiene for homeschooled students and public/private school students (grades 6-12). Public/private school students (n = 245) and homeschooled students (n = 162) completed a survey about sleep patterns and sleep hygiene. Significant school group differences were found for weekday bedtime, wake time, and total sleep time, with homeschooled students waking later and obtaining more sleep. Homeschooled students had later school start times, waking at the same time that public/private school students were starting school. Public/private school students had poorer sleep hygiene practices, reporting more homework and use of technology in the hour before bed. Regardless of school type, technology in the bedroom was associated with shorter sleep duration. Later school start times may be a potential countermeasure for insufficient sleep in adolescents. Future studies should further examine the relationship between school start times and daytime outcomes, including academic performance, mood, and health.