Major Finding: Earlier bedtime predicted significantly higher scores at age 4 years on receptive language, literacy, phonologic awareness, and early math, but not expressive language.
Data Source: An analysis of 8,000 children from the landmark Department of Education–sponsored Early Childhood Longitudinal Study–Birth Cohort.
Disclosures: Dr. Gaylor reported having no financial conflicts in connection with the study.
SAN ANTONIO – Parental emphasis on a consistent bedtime emerged as the strongest predictor of favorable developmental outcomes at 4 years of age in an 8,000-child study.
“Getting parents to set bedtime routines can be an important way to make a significant impact on children's emergent literacy and language skills. Pediatricians can easily promote regular bedtimes with parents and children, behaviors which in turn lead to healthy sleep,” Erika E. Gaylor, Ph.D., said at the meeting.
Preschoolers who averaged fewer than the 11-12 hours of total sleep per 24-hour cycle, recommended in guidelines by the American Academy of Sleep Medicine and other major groups, had significantly lower test scores on language, early math, and literacy skills, reported Dr. Gaylor, an early childhood researcher at SRI International, an independent, nonprofit research and development organization based in Menlo Park, Calif.
Of note, the average nighttime sleep duration of the preschoolers included in this analysis from the landmark Department of Education–sponsored Early Childhood Longitudinal Study–Birth Cohort was 10.5 hours. And since other studies have shown only one-quarter of 4-year-olds still take a daytime nap, that means most U.S. preschoolers are getting 1-2 fewer hours of sleep per 24 hours than recommended.
The analysis was based on a nationally representative sample comprising 8,000 children who underwent standardized, structured assessments of cognition, attention, and emotional development at age 4 years, along with parental phone interviews conducted when the children were aged 9 months and again at 4 years.
Among the key findings:
▸ Three-quarters of children went to bed between 8 and 10 p.m., 22% had a bedtime of 10 p.m. or later, and 3% regularly hit the sack before 8 p.m.
▸ Sixty percent of children woke up between 7 and 9 a.m. Thirty-two percent regularly awakened before 7 a.m.
▸ Children from higher socioeconomic status households went to bed significantly earlier and were 36% more likely to have a rule about bedtime.
▸ African American children went to bed an average of a quarter hour later than did white children and slept significantly less during the night.
▸ Earlier bedtime predicted significantly higher scores at age 4 years on receptive language, literacy, phonologic awareness, and early math, but not expressive language.
Dr. Gaylor noted that this is the largest study of its kind. Its chief limitation was that it relied on parental reports of children's sleep duration, she said.