Dawn E. Elder

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.

Hospital admissions in the first year of life in very preterm infants

Objective: To analyse hospital readmissions to 1 year in infants <33 weeks’ gestation.

Recurrent wheezing in very preterm infants.

AIMS: To document the prevalence of, and identify risk factors for, recurrent wheezing treated with bronchodilators in the first year of life. METHODS: Parental history and neonatal data were collected prospectively in a regional cohort of very preterm infants (< 33 weeks). Data on maternal smoking, siblings at home, breast feeding, respiratory symptoms, and hospital re-admissions were documented at 12 months. RESULTS: Outcome data were available for 525/560 (95%) of survivors. The incidence of recurrent wheeze was 76/525 (14.5%) in very preterm infants and 20/657 (3%) in a cohort of term newborns. Significant risk factors for recurrent wheeze in very preterm infants were parental history of asthma, maternal smoking, siblings at home, neonatal oxygen supplementation at 28 days, 36, and 40 weeks of gestation. CONCLUSIONS: Wheezing respiratory illnesses are common in very preterm infants. The factors involved are similar to those in more mature infants, with the addition of immaturity and neonatal lung injury.

Prone or supine for infants with chronic lung disease at neonatal discharge

Objective:  To determine whether infants with chronic lung disease (CLD), ready for neonatal unit discharge, maintain cardiorespiratory stability while sleeping supine.

Fractal characteristics of breath to breath timing in sleeping infants.

We examined interbreath interval (IBI) time series of 19 term infants during active and quiet sleep for fractal properties using Fano factor analysis. For each time series we calculated the fractal exponent (alpha), comparing alpha for the original time series with two forms of surrogate data, a temporally independent surrogate set and an autoregressive surrogate set. alpha values were normally distributed between 0.79 and -0.22, and did not differ with sleep state. The fractal characteristics of the original time series were not retained in the temporally independent surrogate time series indicating that the distribution of intervals alone was not fractal, but were retained using autoregressive surrogates with an order of 10, suggesting that the fractal properties of the IBI time series were related to correlations between successive breaths. These observations suggest that some of the respiratory variability that occurs during sleep in infants, which in the past has been regarded as stochastic noise, may be the product of deterministic processes.

Sleep Disordered Breathing and Academic Performance: A Meta-analysis

BACKGROUND AND OBJECTIVE: Sleep-disordered breathing (SDB) in children is associated with daytime functioning decrements in cognitive performance and behavioral regulation. Studies addressing academic achievement are underrepresented. This study aimed to evaluate the strength of the relationships between SDB and achievement in core domains and general school performance. METHODS: Data sources included PubMed, Web of Science, CINAHL, and PsycINFO. Studies of school-aged children investigating the relationships between SDB and academic achievement were selected for inclusion in a systematic literature review using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data extracted were converted into standardized mean differences; effect sizes (ES) and statistics were calculated by using random-effects models. Heterogeneity tests (I2) were conducted. RESULTS: Of 488 studies, 16 met eligibility criteria. SDB was significantly associated with poorer academic performance for core academic domains related to language arts (ES –0.31; P < .001; I2 = 74%), math (ES –0.33; P < .001; I2 = 55%), and science (ES –0.29; P = .001; I2 = 0%), and with unsatisfactory progress/learning problems (ES –0.23; P < .001; I2 = 0%) but not general school performance. CONCLUSIONS: Variable definitions of both academic performance and SDB likely contributed to the heterogeneity among published investigations. Clear links between SDB and poorer academic performance in school-age children are demonstrated. ES statistics were in the small to medium range, but nevertheless the findings serve to highlight to parents, teachers, and clinicians that SDB in children may contribute to academic difficulties some children face.

Car seat test for preterm infants: comparison with polysomnography

Objectives: To monitor preterm infants in a cot and a car seat and compare an observed car seat trial with polysomnography (PSG). Design: Non-randomised controlled trial. Setting: Regional neonatal unit. Patients: Preterm infants before discharge. Interventions: Nap PSG respiratory and sleep variables were measured including gastro-oesophageal pH. Nurse observations included respiratory distress, apnoea measured by apnoea alarm, oxygen saturation and heart rate. Infants were studied supine in a cot and then in a car seat. Nursing observations were compared with PSG during the car seat trial only. Criteria for failure of the PSG and observed tests were predefined. Main outcome measures: Difference in respiratory instability between cot and car seat. Concurrence regarding failure of the car seat trial between nurse-observed data and PSG. Results: 20 infants (median gestation 33 weeks (range 28–35 weeks; median postmenstrual age (PMA) at study 36.5 weeks (range 35–38 weeks)) were studied. There were sufficient car seat data on 18 infants for comparison. There were fewer central apnoeas and arousals in the cot than the car seat (p = 0.047 and p = 0.024, respectively). Airway obstruction was not more common in the car seat. Younger PMA at time of study predicted failure in both car seat (p = 0.022) and cot (p = 0.022). The nurse-observed test had low sensitivity for predicting PSG failure but more accurately predicted airway obstruction on PSG. Conclusions: Immature infants exhibit respiratory instability in cots and car seats. A car seat test does not accurately detect all adverse events during sleep in the seat.

Interventions with a sleep outcome for children with cerebral palsy or a post-traumatic brain injury: A systematic review

The purpose of this study was to conduct a systematic literature review on interventions for sleep problems in children (aged 0-12 years) with cerebral palsy (CP) or traumatic brain injury (TBI). The literature describes sleep disorders as common in both conditions. Criteria were expanded to include interventions for other medical conditions where sleep was measured as an outcome. No interventions specifically designed to improve sleeping in children with CP or TBI were found. A literature search was conducted of five databases (Ovid MEDLINE, EMBASE, PsychINFO, CINAHL, and the Cochrane Database) from January 1 1990, to June 2011. The search terms [infant (age 0-23 months) or child, preschool (age 2-5 years) or child (age 6-12 years)] were used, with key terms related to CP and TBI. The search yielded 491 articles; 19 were relevant for CP, one for TBI. For CP, if the intervention improved the symptom/s targeted as primary outcome/s, sleep (measured as a secondary outcome) also improved. Few studies used objective measures of sleep, so efficacy could not be assessed. Only four studies were randomized controlled trials. Interventions were diverse. Where melatonin was used for CP patients with sleep problems/disorders, several related to phase or sleep maintenance disorders, improvements in sleep latency and night waking were consistently found, and in some subjects, improvements in total sleep time. No studies using melatonin studied CP patients exclusively. The one study where sleep was measured as a secondary outcome for TBI was of limited value. In conclusion, more well-designed studies are necessary to advance evidence-based treatments in the area of sleep problems for these chronic pediatric conditions.

Respiratory variability in preterm and term infants: Effect of sleep state, position and age.

The influence of sleep state and position on respiratory variability (RV) was studied in 13 preterm infants (PTIs) and 19 term infants (TIs). Temporally matched epochs of nasal pressure and oxygen saturation (Spo₂) data were extracted from nap polysomnography. Inspiratory onset times (I) were determined, and variability measures of the I-I interval compared in quiet sleep and active sleep, prone and supine and with age. Sleep state influenced respiratory variability (RV) in PTI and TI but Spo₂ only varied with sleep state in PTI (p=0.03). Position had no effect on RV in TI but influenced the standard deviation of ventilatory frequency (SDf) in PTI (p=0.04). Age did not influence RV in PTI but SDf and the coefficient of variation of ventilatory frequency (CVf) decreased in TI from birth to 3 months. These data confirm sleep state as the predominant influence on RV in healthy term and convalescent preterm infants, with horizontal prone positioning having little effect when sleep state is controlled for.

Cardioventilatory coupling in preterm and term infants: Effect of position and sleep state

This study documented the effect of position on cardioventilatory coupling (CVC), the triggering of inspiratory onset by a preceding heartbeat, in infants. Cardiorespiratory signals and corresponding oxygen saturation (SpO(2)) were downloaded from Quiet Sleep (QS) and Active Sleep (AS) in prone and supine from preterm (PT) and term (T) infants. Inspiratory onsets (I) and timing of the corresponding ECG R wave were determined and R-R and R-I intervals calculated. The RI(-1) interval (time between inspiration and the preceding R wave) dispersion was measured using proportional Shannon Entropy of the RI(-1) interval (SH(α)), to provide a quantitative measure of CVC. CVC was more frequently seen in QS in PT (p=0.002) and T (p=0.02) infants but not influenced by position (p=0.71, p=0.46). CVC correlated with SpO(2) in PT (r=-0.230, p=0.03) but not T infants (r=0.085, p=0.34). These data imply an augmentation of cardiac influence on ventilatory rhythm in infants in QS. In preterm infants CVC may have a role in supporting oxygenation.