Children who regularly slept 10-plus hours per night, particularly just before starting kindergarten, transitioned more successfully to kindergarten than those with less regular sleeping patterns, an observational study found. The effect held across the kindergarten year regardless of socioeconomic and health covariates, according to a new study by Douglas M. Teti, PhD, a developmental scientist and a professor of pediatrics at Penn State University, University Park, and colleagues.
“These effects were ubiquitous, extending to socioemotional learning engagement and academic domains,” they wrote online in Pediatrics
Dr. Douglas M. Teti
Furthermore, it was the regularity of sufficient nocturnal sleep that appeared to be more important for school adjustment than overall amounts of sleep accumulated across the day or the proportion of 24-hour periods in which children got 10 or more hours of sleep.
The American Academy of Sleep Medicine has recommended that 3- to 5-year-olds get 10-13 hours of sleep per day, including naps.
The findings by Dr. Teti’s group suggest that family-based interventions to establish consistent patterns of sufficient nighttime sleep should begin 5 or 6 months before the start of kindergarten.
“The importance of sleep as a predictor of school functioning in children is well-established, but relatively less is known about how sleep impacts children as they make their first transition into formal schooling,” Dr. Teti told this news organization. “School readiness and adjustment can be impacted by many factors, including socioeconomic status, child health, and missed days of school, but few studies have isolated the role of sleep in the transition to kindergarten net of these other influences, and few studies have examined the role that sleep plays on children’s school functioning throughout the full kindergarten year.”
The study
During 2016-2019, the researcher recruited 230 families from three Pennsylvania school districts, of which 221 completed the study. At several time points, the study examined three different measures of child sleep duration in 7-day bursts: at pre-kindergarten (July to August), early kindergarten (late September), mid-kindergarten (late November), and late kindergarten (mid-to-late April), using wrist actigraphy. These measures included:
- mean amounts of child sleep per 24-hour period across the full week
- proportion of 24-hour periods per week that children slept 10 or more hours
- proportion of nighttime sleep periods per week that children slept 10 or more hours
Outcomes at the designated school year time points were provided by 64 teachers blinded to the pupils’ sleep histories and by assessments administered by project staff.
Among the sleep measures examined, regularity of nighttime sleep involving 10 or more hours of sleep over the nocturnal period, especially at the pre-kindergarten stage, consistently predicted more favorable outcomes in socioemotional, learning engagement, and academic domains. These findings were controlled for income-to-poverty threshold ratios, child health status, and number of missed school days.
The study results generally align with those of previous studies, showing the importance of sleep for children’s school functioning, Dr. Teti told this news organization. “But they differed significantly in terms of finding that it was the regularity of 10-plus hours concentrated during the nighttime sleep period that was most important for predicting school adjustment, in particular, regular or sufficient sleep that occurred prior to the start of kindergarten.”
Calling the study “thought provoking,” Michael B. Grosso, MD, chair of pediatrics at Huntington (N.Y.) Hospital, said it confirms a robust correlation between total sleep duration and outcomes important to successful adjustment to kindergarten. “And we find out that uninterrupted sleep time of 10 hours or more seems to matter as well.”
In his view, the biggest limitation to the analysis is the one inherent to any observational study, “which is that association cannot prove causality. The authors did attempt to control for other health factors, but that can be hard to do,” he said. “The point is that if a child faces any of several health challenges, from sleep apnea to uncontrolled asthma, to ADHD or an autistic spectrum disorder, those issues will cause disrupted, abnormal sleep and also interfere with the outcomes the study addresses. In other words, it’s hard to know if sleep is affecting kindergarten adjustment or whether some X factor is affecting sleep and also affecting kindergarten performance.”
Getting children into bed earlier in long bright evenings of spring and summer before onset of kindergarten may not be easy, Dr. Teti acknowledged. “Arranging children’s sleep schedule as they approach kindergarten so that most, if not all, of their sleep takes place during the night – and as a corollary, reducing the frequency of naps during the day – should help children shift into sleeping nighttime primarily if not exclusively,” he said.
If necessary, he added, parents can work with sleep professionals to gradually concentrate children’s sleep during the night. They should normalize earlier bedtimes by reducing access to electronic screens before bedtime and removing televisions from their bedrooms. “A consistent bedtime routine should be a central feature of parental attempts to shape better, more regular sleep in their children.”
Dr. Grosso added that pediatricians need to talk about the importance of consistent routines and especially adequate sleep when counseling parents during pre-school health supervision visits. “And as the authors mention, it’s hard to ensure good sleep hygiene for children if parents aren’t also getting a good night sleep. It all goes together.”
This study was supported by the National Institutes of Health. The authors had no competing interests to declare. Dr. Grosso disclosed no relevant conflicts of interest.