Optimal Sleep Duration for Teens Different between Academics and Mental Health

While few people argue over the importance of sleep,  just how much sleep is optimal has remained a surprisingly elusive question.  Complicating things further is the possibility that the best amount might differ between domains such as academic achievement and optimal mental health as well as the importance of other sleep parameters such as the amount of day-to-day variation.

To address some of these questions a research group from UCLA and Arizona State studied 421 9th and 10th grade Mexican-American adolescents in the Los Angeles area.   The subjects recorded their sleep duration daily for two weeks.  A measure of sleep variability was also calculated.  Grade point average, standardized test scores, and school absences were also obtained.  Levels of emotional-behavioral problems were assessed using the Child Behavior Checklist (of course!).  The participants repeated this procedure about one year later.

The researchers found that the average amount of sleep for 9th, 10th, and 11th graders 8.1, 8.0, and 7.9 hours, respectively with about 1.4 hours of variation across nights.  Non-linear associations were found between sleep duration and academic achievement with the optimal level found to be about 7.5 hours for GPA and around 7 hours for a standardized English test, with no association found with a standardized math test.  A different optimal point, however, was found for behavior problems, with the lowest levels associated at approximately 9 hours per night.  The implications for sleep on mental health appeared stronger than they did for academic achievement.  More sleep variability was also significantly related to higher levels of behavioral problems, although the pattern was less evident and more mixed with regard to academics.

The authors concluded that there might be a trade-off in the optimal level of sleep with regards to academic achievement and mental health with more sleep related to better mental health at the slight cost of some academic achievement.  Of course, causation was not established in this study and it could be that mental health problems are associated with reduced sleep rather than the other way around.   


Fuligni AJ, et al.  Adolescent Sleep Duration, Variability, and Peak Levels of Achievement and Mental Health.  Child Development, epub ahead of print

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