Barbara C. Galland

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

This is a systematic review of the scientific literature with regard to normal sleep patterns in infants and children (0-12 years). The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Mean and variability data for sleep duration, number of night wakings, sleep latency, longest sleep period overnight, and number of daytime naps were extracted from questionnaire or diary data from 34 eligible studies. Meta-analysis was conducted within age-bands and categories. In addition, fractional polynomial regression models were used to estimate best-fit equations for the sleep variables in relation to age. Reference values (means) and ranges (±1.96 SD) for sleep duration (hours) were: infant, 12.8 (9.7-15.9); toddler/preschool, 11.9 (9.9-13.8); and child, 9.2 (7.6-10.8). The best-fit (R(2)=0.89) equation for hours over the 0-12 year age range was 10.49-5.56×[(age/10)^0.5-0.71]. Meta-regression showed predominantly Asian countries had significantly shorter sleep (1h less over the 0-12 year range) compared to studies from Caucasian/non-Asian countries. Night waking data provided 4 age-bands up to 2 years ranging from 0 to 3.4 wakes per night for infants (0-2 months), to 0-2.5 per night (1-2 year-olds). Sleep latency data were sparse but estimated to be stable across 0-6 years. Because the main data analysis combined data from different countries and cultures, the reference values should be considered as global norms.

Sleep position, autonomic function, and arousal

AIMS To investigate and compare heart rate variability (HRV) and responses of heart rate and arousal to head-up tilting in infants sleeping prone and supine. METHODS Thirty seven healthy infants aged 2–4 months were studied. HRV was measured for 500 beats while they were in a horizontal position. Subjects were then tilted 60° head-up, and heart rate recorded over 1 minute and arousal responses observed. Data were collected during both quiet and active sleep for both prone and supine sleep positions. RESULTS HRV, as assessed by the point dispersion of Poincaré plots, was significantly reduced in the prone position for both sleep states. Sleep position did not influence the changes in heart rate seen during a head-up tilt. Full awakening to the tilt was common in active sleep but significantly less so in the prone position (15% of prone tests vs 54% supine). Full awakening to the tilt rarely occurred during quiet sleep in either sleep position. CONCLUSION This study provides some evidence that blunted arousal responses and/or altered autonomic function are a feature of the prone sleeping position. Decreased HRV may be a sign of autonomic impairment. It is seen in many disease states and in infants who later die of sudden infant death syndrome (SIDS).

Factors Affecting Heart Rate Variability and Heart Rate Responses to Tilting in Infants Aged 1 and 3 Months

Heart rate variability (HRV) and heart rate (HR) responses following a 60° head-up tilt were measured in 60 infants at 1 and 3 mo of age to investigate the effects on these of age, sleep state, sleep position, and mothers smoking status. HRV was determined from Poincaré plots of 500 sequential RR intervals to measure overall variability derived from the SDRR of this plot, and instantaneous variability derived from the SDΔRR. HR responses to the tilt were measured as changes in RR interval length from rest to immediately following the tilt and again once a stable pattern was reached. SDRR and SDΔRR increased 20 and 40%, respectively, with age (p < 0.0001), SDRR was higher in active sleep (AS) than quiet sleep (QS, +72%, p < 0.0001)) but both measures of variability (SDRR and SDΔRR) were lower in the prone position compared with supine (−18%, p < 0.0001). However, several findings were dependent on the basal RR interval, thus the age effect disappeared once RR interval was taken into account, sleep state remained an important factor and the lower variability when prone now became a difference of −3% (p = 0.034). The tilt generally provoked a reflex tachycardia followed by a bradycardia and settling to a stable HR level below, at, or above baseline within 30 s. The more unusual responses were no HR change, sustained tachycardia or sustained bradycardia (15% of total). These were more likely to occur in younger infants (p = 0.008) and in AS (p < 0.0001). No changes were seen in any of the cardiac indices related to maternal smoking status. The findings confirm several reports indicating that prone sleeping damps some physiologic responses. The data emphasize the need to consider basal heart rate, and sleep position as well as sleep state in autonomic function testing during infant sleep.

Rebreathing expired gases from bedding: a cause of cot death?

The reported association of cot death and sleeping prone could be due to rebreathing of expired gases. A mechanical model simulating the respiratory system of an infant, exhaling warm humidified air with an end tidal carbon dioxide of 5%, has been used to investigate this. Some commonly used bedding materials caused an accumulation of carbon dioxide of 7% to over 10% with the model lying face down. This phenomenon persisted even with the head inclined at 45 degrees, but only on very soft materials, and could be a cause of cot death in a baby unresponsive to asphyxial blood gas changes. A coir fibre mattress allowed complete dispersal of exhalate as did a rubber sheet between any mattress and the covering sheet.

Participation in research: Informed consent, motivation and influence

Objective: To investigate the process and quality of informed consent, motivation and influence in parents who were invited to enrol their baby in a research project.

Sleep hygiene intervention for youth aged 10 to 18 years with problematic sleep: a before-after pilot study

BackgroundThe current study aimed to examine the changes following a sleep hygiene intervention on sleep hygiene practices, sleep quality, and daytime symptoms in youth.MethodsParticipants aged 10–18 years with self-identified sleep problems completed our age-appropriate F.E.R.R.E.T (an acronym for the categories of Food, Emotions, Routine, Restrict, Environment and Timing) sleep hygiene programme; each category has three simple rules to encourage good sleep. Participants (and parents as appropriate) completed the Adolescent Sleep Hygiene Scale (ASHS), Pittsburgh Sleep Quality Index (PSQI), Sleep Disturbance Scale for Children (SDSC), Pediatric Daytime Sleepiness Scale (PDSS), and wore Actical® monitors twice before (1 and 2 weeks) and three times after (6, 12 and 20 weeks) the intervention. Anthropometric data were collected two weeks before and 20 weeks post-intervention.ResultsThirty-three youths (mean age 12.9 years; M/F = 0.8) enrolled, and retention was 100%. ASHS scores significantly improved (p = 0.005) from a baseline mean (SD) of 4.70 (0.41) to 4.95 (0.31) post-intervention, as did PSQI scores [7.47 (2.43) to 4.47 (2.37); p < 0.001] and SDSC scores [53.4 (9.0) to 39.2 (9.2); p < 0.001]. PDSS scores improved from a baseline of 16.5 (6.0) to 11.3 (6.0) post- intervention (p < 0.001). BMI z-scores with a baseline of 0.79 (1.18) decreased significantly (p = 0.001) post-intervention to 0.66 (1.19). Despite these improvements, sleep duration as estimated by Actical accelerometry did not change. There was however a significant decrease in daytime sedentary/light energy expenditure.ConclusionsOur findings suggest the F.E.R.R.E.T sleep hygiene education programme might be effective in improving sleep in children and adolescents. However because this was a before and after study and a pilot study with several limitations, the findings need to be addressed with caution, and would need to be replicated within a randomised controlled trial to prove efficacy.Trial registrationAustralian New Zealand Clinical Trials Registry: ACTRN12612000649819

Helping children sleep

Sleep problems in children are very common and affect both the child and parents. The common problems are bedtime resistance, delayed sleep onset and frequent night waking. This review summarises current non-pharmacological practices and intervention options to aid healthy children sleep. Children may benefit from good sleep hygiene practices, which include a consistent routine for bed and consistent bedtime, a quiet darkened and warm bedroom, a consistent wake time and daytime exercise. In more problematic cases children benefit from a sleep programme. Programmes are many and effective, and include extinction or extinction-based procedures, and scheduled awakenings. An extinction programme alone, although highly effective, is difficult for parents to comply with. Modifications of the extinction programme show promise but need further evaluation. Identifying and managing sleep problems in childhood may improve health, including emotional well-being, in adolescence and adulthood.

Bed-sharing and the infant’s thermal environment in the home setting

Aims: To study bed-sharing and cot-sleeping infants in the natural setting of their own home in order to identify differences in the thermal characteristics of the two sleep situations and their potential hazards. Methods: Forty routine bed-sharing infants and 40 routine cot-sleeping infants aged 5–27 weeks were individually matched between groups for age and season. Overnight video and physiological data of bed-share infants and cot-sleeping infants were recorded in the infants’ own homes including rectal, shin, and ambient temperature. Results: The mean rectal temperature two hours after sleep onset for bed-share infants was 36.79°C and for cot-sleeping infants, 36.75°C (difference 0.05°C, 95% CI −0.03 to 0.14). The rate of change thereafter was higher in the bed-share group than in the cot group (0.04°C v 0.03°C/h, difference 0.01, 0.00 to 0.02). Bed-share infants had a higher shin temperature at two hours (35.43 v 34.60°C, difference 0.83, 0.18 to 1.49) and a higher rate of change (0.04 v −0.10°C/h, difference 0.13, 0.08 to 0.19). Bed-sharing infants had more bedding. Face covering events were more common and bed-share infants woke and fed more frequently than cot infants (mean wake times/night: 4.6 v 2.5). Conclusions: Bed-share infants experience warmer thermal conditions than those of cot-sleeping infants, but are able to maintain adequate thermoregulation to maintain a normal core temperature.

Changes in Behavior and Attentional Capacity after Adenotonsillectomy

The objective of this study was to quantify behavioral and attention capacity changes in children aged 4–11 y before and 3 mo after adenotonsillectomy (A/T). Overnight cardiorespiratory recordings were performed in 61 “behaviorally normal” children 1 wk before A/T. Tests of sustained attention using visual and auditory continuous performance tests (CPT) were completed by children 1 wk before and 3 mo after A/T. Behavioral Assessment Scales for Children (BASC) and a sleep questionnaire were completed by the parent/s at these same times. Results from overnight cardiorespiratory recordings showed that the children had mild sleep-related breathing disorders (SRBD) preoperatively with a mean apnea/hypopnea index of 3.0/h and a movement awakening index of 2.5/h. The majority had parent-perceived sleep and breathing difficulties that significantly improved post-A/T. BASC T scores for externalizing and internalizing behaviors improved post-A/T, e.g., behavioral symptom index mean pre-A/T was 56.2 (95% confidence interval, 52.8–59.6) compared with 50.9 (48.5–53.5) post-A/T. Some measures indicative of impulsivity and attentiveness obtained from the visual CPT before surgery, improved post-A/T, but no change was observed in any auditory CPT measures. Our data confirm improvements in subjective measures of sleep problems in children treated for SRBD and strengthen the notion of treating the disorder, not only related to the obvious clinical condition but also to the underlying sleep problems and adverse effects on daytime behavior and attention.

Prone versus supine sleep position: A review of the physiological studies in SIDS research

Abstract:  A number of physiological studies, published over the last 10 years, have investigated the links between prone sleeping and sudden infant death syndrome (SIDS). This review evaluates those studies and derives an overview of the different affects of sleeping prone or supine in infancy. Generally, compared with the supine, the prone position raises arousal and wakening thresholds, promotes sleep and reduces autonomic activity through decreased parasympathetic activity, decreased sympathetic activity or an imbalance between the two systems. In addition, resting ventilation and ventilatory drive is improved in preterm infants, but in older infants (>1 month), there is no improvement in ventilation, and in 3‐month‐old infants, the position is adverse in terms of poorer ventilatory drive (in active sleep only). The majority of findings suggest a reduction in physiological control related to respiratory, cardiovascular and autonomic control mechanisms, including arousal during sleep in the prone position. Since the majority of these findings are from studies of healthy infants, continued reinforcement of the supine sleep recommendations for all infants is emphasized.