This study describes parental expectations for sleep-wake patterns in healthy kindergarten children and explores their relation to children's sleep quality and parental distress. Data analysis of 54 mother-child dyads (age range of the children: 4–7 years) indicated that parental expectations for children's sleep-wake patterns differ between scheduled and free days and depend on children's chronotype. Mothers of children with late chronotype showed less adequate expectations for children's sleep onset time than mothers of children with early chronotype (e.g., morning types). Furthermore, children of mothers with less adequate expectations for children's sleep onset time on scheduled days had longer settling periods during which sleep rituals may take place (r = 0.31, P ≤ 0.05), spent more time in bed than they actually sleep (r = 0.35, P ≤ 0.01), and had more frequently difficulties falling asleep (r = 0.33, P ≤ 0.01). However, less adequate expectations for children's sleep onset time were not associated with parental distress (P > 0.05). We conclude that parental expectations about their children's sleep play a key role in understanding normal and abnormal sleep during childhood.

Purpose of review

Sleep–wake problems such as night wakings, excessive crying, or difficulties in falling asleep are frequent behavioral issues during childhood. Maturational changes in sleep and circadian regulation likely contribute to the development and maintenance of such problems. This review highlights the recent research examining bioregulatory sleep mechanisms during development and provides a model for predicting sleep–wake behavior in young humans.

Recent findings

Findings demonstrate that circadian and sleep homeostatic processes exhibit maturational changes during the first two decades of life. The developing interaction of both processes may be a key determinant of sleep–wake and crying behavior in infancy. Evidence shows that the dynamics of sleep homeostatic processes slow down in the course of childhood (i.e., sleep pressure accumulates more slowly with increasing age) enabling children to be awake for consolidated periods during the day. Another current topic is the adolescent sleep phase delay, which appears to be driven primarily by maturational changes in sleep homeostatic and circadian processes.

Summary

The two-process model of sleep regulation is a valuable framework for understanding and predicting sleep–wake behavior in young humans. Such knowledge is important for improving anticipatory guidance, parental education, and patient care, as well as for developing appropriate social policies.

Background

Sleep onset and maintenance problems are a frequent complaint after traumatic events in children. However, the association of traumatic experiences and disturbed sleep remains to be explained.

Objective

To examine the incidence of sleep onset and maintenance problems in children after road traffic accidents and identify potential predictors of sleep onset and maintenance problems, including putative psychopathological mechanisms as well as stressors affecting the family system.

Method

In 33 children treated for injuries after road traffic accidents, sleep and measures of psychopathology were assessed 10 days, 2 months, and 6 months after hospital admission. The predictive value of four clusters of predictor variables for children's sleep onset and maintenance problems was prospectively tested by multiple regression analyses. These clusters included socio-demographic, injury- and accident-related, and psychopathological variable clusters as well as factors reflecting stressors concerning mothers and family.

Results

Children suffering from posttraumatic stress reported a prolonged subjective sleep latency. The severity of sleep onset and maintenance problems was predicted by female sex and the child's as well as mothers’ posttraumatic stress disorder (PTSD) severity.

Conclusions

Sleep onset and maintenance problems in children after trauma appear to result from a complex interaction of multiple factors. Our findings support the transactional model of sleep-wake regulation that bears implications for the development of adequate intervention strategies.

Background

A number of radiogrammetrical metacarpal indices are in use, some of which have been adapted for children.

Objective

The purpose of this study was to compare four known indices—bone mineral density (BMD), relative cortical area, Exton-Smith index, bending breaking resistance index—and the more recently defined pediatric bone index (PBI) according to the two criteria of minimum height dependence and minimum variability in children of equal bone age.

Materials and methods

A total of 3,121 left-hand radiographs from 231 healthy Caucasian children ranging in age from 3 to 19 years old were analysed using BoneXpert®, a programme for automatic analysis of hand radiographs and assessment of bone age.

Results

Dependence on height for chronological age or bone age and the mean relative standard deviation were lowest in the PBI for both genders pooled. The differences in height dependence were statistically significant and are shown to be clinically relevant. Reference data for PBI are presented.

Conclusion

PBI may be a better indicator than BMD for bone health in children; however, verification in a clinical group is needed.

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.

Individual differences in circadian phase preference (“chronotype”) are linked to sleep schedule variability, psychosocial functioning, and specific properties of the circadian clock. While much is known about the development, distribution, and variability of chronotype in adolescents and adults, assessment in prepubertal children has been hindered by a lack of appropriate, reliable, and valid measures. This study presents a detailed description of the assessment of children’s chronotype by the Children’s ChronoType Questionnaire (CCTQ). The CCTQ is a parent-report, 27-item mixed-format questionnaire resulting in multiple measures of chronotype in 4- to 11-yr-old children: the midsleep point on free days (MSF), a morningness/eveningness scale (M/E) score, and a five-point chronotype (CT) score. The study provides validity data using actigraphy as well as test-retest reliability data for all three chronotype measures and sleep/wake parameters. Overall, the findings indicate moderate to strong agreement between the three measures, adequate associations between chronotype measures and sleep/wake parameters assessed by actigraphy, and excellent temporal stability (reliability). (Author correspondence: oskar.jenni@kispi.uzh.ch)