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

Sleep patterns and sleep disturbances among Chinese school-aged children: prevalence and associated factors

OBJECTIVE

The study aimed to (1) characterize sleep patterns and sleep disturbances among Chinese school-aged children, (2) determine the prevalence of their short sleep duration and sleep disturbances based on clinical cutoffs, and (3) examine possible factors (socio-demographic factors and emotional/behavioral problems) that are associated with sleep disturbances.

METHODS

A large representative sample of 912 children aged 6-14years was recruited from Shenzhen, China. Their parents completed the Children's Sleep Habits Questionnaire (CSHQ) and the Strengths and Difficulties Questionnaire (SDQ).

RESULTS

The mean bedtime was 9:45pm (SD=1h 11min), mean wake-up time was 7:03am (SD=31min), mean sleep duration was 9h 14min (SD=46min), and 23.8% of the children had sleep duration <9h. Overall, 69.3% of the children suffered from global sleep disturbances (CSHQ total score >41). Bedtime resistance (22.9%), sleep anxiety (22.1%), sleep duration (21%) and daytime sleepiness (20%) were the most prevalent sleep disturbances; followed by sleep disordered breathing (12.1%), parasomnias (9.4%), sleep onset delay (6.9%), and night waking (5.2%). The prevalence of specific sleep disturbances ranged from 3.2% (falling asleep while watching television) to 81.9% (awakening by others in the morning). Correlations between most domains of sleep disturbances and emotional/behavioral problems were statistically significant (p<0.05 or p<0.01). Hierarchical multiple regression analysis revealed that gender (β=0.10, p<0.01), school grade (β=-0.09, p<0.05), co-sleeping (β=0.25, p<0.01), emotional symptoms (β=0.24, p<0.01), conduct problems (β=0.09, p<0.05), and hyperactivity (β=0.17, p<0.01) accounted for significant variance in CSHQ total score.

CONCLUSIONS

Short sleep duration and sleep disturbances are prevalent among Chinese school-aged children. Sleep disturbances are associated with gender, school grade, co-sleeping, emotional symptoms, conduct problems, and hyperactivity.

Continuity and change in infants' sleep from 8 to 14 months: a longitudinal actigraphy study

In this report changes and stability in sleep-wake characteristics, at the latter part of infancy, were examined. The sample comprised of 34 healthy infants whose sleep was assessed by means of actigraphy at 8, 10, 12 and 14 months. The results indicated that while sleep schedules did not change significantly from 8 to 14 months, sleep consolidation continued across time. Age 12 months stands out in that sleep disruption was unrelated to whether or not the child was a frequent nightwaker before and/or after the 1st birthday. The findings demonstrate the importance of investigating sleep longitudinally using multiple time scales.

Preschoolers' daytime respiratory sinus arrhythmia and nighttime sleep

We examined the association between preschoolers' (N=29; 20 boys; M age = 3.99 years, SD=.69) daytime parasympathetic nervous system (PNS) activity indexed by respiratory sinus arrhythmia (RSA) and their nighttime sleep. Children's baseline RSA was assessed in the laboratory. Sleep was monitored for seven consecutive nights at the child's home via actigraphy and the following sleep parameters were derived: sleep minutes, sleep activity index and sleep efficiency. Regression analyses showed that after controlling for potential confounds, higher RSA was a predictor of lower sleep activity and higher sleep efficiency. Results highlight the importance of physiological regulation for the sleep of healthy preschool children.

Sleep-disordered breathing in a population-based cohort: behavioral outcomes at 4 and 7 years

OBJECTIVES

Examine statistical effects of sleep-disordered breathing (SDB) symptom trajectories from 6 months to 7 years on subsequent behavior.

METHODS

Parents in the Avon Longitudinal Study of Parents and Children reported on children's snoring, mouth breathing, and witnessed apnea at ≥2 surveys at 6, 18, 30, 42, 57, and 69 months, and completed the Strengths and Difficulties Questionnaire at 4 (n = 9140) and 7 (n = 8098) years. Cluster analysis produced 5 "Early" (6-42 months) and "Later" (6-69 months) symptom trajectories ("clusters"). Adverse behavioral outcomes were defined by top 10th percentiles on Strengths and Difficulties Questionnaire total and subscales, at 4 and 7 years, in multivariable logistic regression models.

RESULTS

The SDB clusters predicted ≈20% to 100% increased odds of problematic behavior, controlling for 15 potential confounders. Early trajectories predicted problematic behavior at 7 years equally well as at 4 years. In Later trajectories, the "Worst Case" cluster, with peak symptoms at 30 months that abated thereafter, nonetheless at 7 years predicted hyperactivity (1.85 [1.30-2.63]), and conduct (1.60 [1.18-2.16]) and peer difficulties (1.37 [1.04-1.80]), whereas a "Later Symptom" cluster predicted emotional difficulties (1.65 [1.21-2.07]) and hyperactivity (1.88 [1.42-2.49]) . The 2 clusters with peak symptoms before 18 months that resolve thereafter still predicted 40% to 50% increased odds of behavior problems at 7 years.

CONCLUSIONS

In this large, population-based, longitudinal study, early-life SDB symptoms had strong, persistent statistical effects on subsequent behavior in childhood. Findings suggest that SDB symptoms may require attention as early as the first year of life.

Reliability of home-based physiological sleep measurements in snoring and non-snoring 3-year olds

PURPOSE

To study snoring and non-snoring 3-year olds in their own homes and to establish reference values and night-to-night variability of physiological measurements taken during sleep.

METHODS

One hundred and sixty-six children, aged 3.2-4.0 years, identified as at high (n = 83, M/F = 1.5:1) or low (n = 83, M/F = 1.4:1) risk for persistent snoring, as rated by a parent, wore a sleep screening system (Grey Flash) for up to five consecutive nights, to measure snoring, oxygen saturation, heart rate, movement, sleep efficiency, and sleep timing.

RESULTS

The snoring group snored 25% of their total sleep time, while the non-snoring group snored just 7.6%. Reliability estimates were calculated, using intraclass correlations to establish the reliability of single recordings and the Spearman-Brown prophecy formula to estimate reliability over multiple recordings. Snoring (percent), turn index (number of turns per hour), and mean heart rate were adequately assessed in both groups with one recording night (all intraclass correlation coefficients (ICCs) ≥0.70). Furthermore, mean SpO(2) was measured with sufficient reliability with two recordings in non-snorers (ICC = 0.71), while five recording nights were necessary to reach reliability in snorers (ICC = 0.71). SpO(2) nadir did not reach adequate reliability in either group even after seven recording nights.

CONCLUSIONS

Our results showed that snoring can be measured reliably at home with just one recording night, whereas most other physiological sleep measures require two or more recordings.

Prevention of Overweight in Infancy (POI.nz) study: a randomised controlled trial of sleep, food and activity interventions for preventing overweight from birth

BACKGROUND

Rapid weight gain during the first three years of life predicts child and adult obesity, and also later cardiovascular and other morbidities. Cross-sectional studies suggest that infant diet, activity and sleep are linked to excessive weight gain. As intervention for overweight children is difficult, the aim of the Prevention of Overweight in Infancy (POI.nz) study is to evaluate two primary prevention strategies during late pregnancy and early childhood that could be delivered separately or together as part of normal health care.

METHODS/DESIGN

This four-arm randomised controlled trial is being conducted with 800 families recruited at booking in the only maternity unit in the city of Dunedin, New Zealand. Mothers are randomised during pregnancy to either a usual care group (7 core contacts with a provider of government funded "Well Child" care over 2 years) or to one of three intervention groups given education and support in addition to "Well Child" care: the Food, Activity and Breastfeeding group which receives 8 extra parent contacts over the first 2 years of life; the Sleep group which receives at least 3 extra parent contacts over the first 6 months of life with a focus on prevention of sleep problems and then active intervention if there is a sleep problem from 6 months to 2 years; or the Combination group which receives all extra contacts. The main outcome measures are conditional weight velocity (0-6, 6-12, 12-24 months) and body mass index z-score at 24 months, with secondary outcomes including sleep and physical activity (parent report, accelerometry), duration of breastfeeding, timing of introduction of solids, diet quality, and measures of family function and wellbeing (parental depression, child mindedness, discipline practices, family quality of life and health care use). This study will contribute to a prospective meta-analysis of early life obesity prevention studies in Australasia.

DISCUSSION

Infancy is likely to be the most effective time to establish patterns of behaviour around food, activity and sleep that promote healthy child and adult weight. The POI.nz study will determine the extent to which sleep, food and activity interventions in infancy prevent the development of overweight.

TRIAL REGISTRATION

Clinical Trials NCT00892983. Prospective meta-analysis registered on PROSPERO CRD420111188. Available from http://www.crd.york.ac.uk/PROSPERO.