The question of how much sleep children and adolescents need seems simple on its surface, but is actually not that easy to answer definitively. The question is almost always raised in terms of how many hours of sleep are needed, and typically the question ends there. Not always stated but implicit in the question is how many hours are needed for optimal functioning cognitively and academically, optimal emotional well-being, and optimal health. Further, no consideration is usually given to quality or day-to-day variability in sleep, both of which may well be more important than the number of hours needed.
The most frequent source for answering the question is “expert opinion”. It assumed that professionals such as pediatricians, researchers who study sleep, and sleep medicine practitioners have a collective body of wisdom that derives from knowledge about a multitude of individual children seen in clinical practice and studied in research projects over many years.
In 2013, a group of Australian researchers questioned whether or not sufficient evidence existed to justify making any recommendations about sleep needs of children and adolescents (Matricciani et al. 2013). They argued that sufficient evidence to support recommendations had not been provided and suggested several ways of conducting studies that would be helpful. One way suggested was to conduct studies of “dose-response relationships” similar to what would be done to determine the optimal dose of a drug in yielding the optimal response. In such a study, an inverted U-shaped curve would be obtained, such that more sleep would provide more benefit up to a deflection point where more sleep beyond the point would not yield a further benefit in the desired outcome, and would even perhaps begin to show diminishing benefits. This kind of relationship is very likely in the case of sleep, since it is already known that in some cases, such as depression, both sleeping less than usual and sleeping more than usual are problematic.
A study has now been published that examines dose-related relationships for sleep and both academic achievement and socioemotional measures. In the journal, Child Development, Fuligni and colleagues (2017) report on a study of 421 15-year-olds, where they had participants track sleep duration and variability from night to night over a two-week period. They compared sleep data with GPA, standardized achievement test scores, and self-reported socioemotional adjustment—internalizing (e.g depression; anxiety) and externalizing problems (e.g. misbehavior). For socioemotional adjustment, they found that 8.75 to 9 hours of sleep was optimal, which is in line with most guidelines that have been recommended by experts. But for academic outcomes, 7 to 7.5 hours was found, which is well below what experts recommend (8-10 hours for teenagers). One interpretation of the latter result is there is a subset of teenagers who stay up later at night to study. But Fuligni et al (2017) suggest that those who do so may be trading better emotional health for higher achievement. They also found that greater variability was associated with poorer mental health, stating that:
“…reductions of sleep for the sake of incremental gains in academic performance could have negative implications for mental health. Additionally, promoting healthy sleep behaviors for the sake of improved mental health should include efforts to minimize the variation in adolescents’ sleep duration…” (p.10)
Fuligni, A. J., Arruda, E. H., Krull, J. L., & Gonzales, N. A. (2017, in press). Adolescent sleep duration, variability, and peak levels of achievement and mental health. Child Development. doi:10.1111/cdev.12729
Hirshkowitz, M., Whiton, K., Albert, S. M., Alessi, C., Bruni, O., DonCarlos, L., ... & Neubauer, D. N. (2015). National Sleep Foundation’s sleep time duration recommendations: Methodology and results summary. Sleep Health, 1(1), 40-43.
Matricciani, L., Blunden, S., Rigney, G., Williams, M. T., & Olds, T. S. (2013). Children’s sleep needs: Is there sufficient evidence to recommend optimal sleep for children. Sleep, 36(4), 527-534.