Is There an Optimal Sleep Duration for Adolescents?

A new study finds ideal sleep duration differs in adolescents for peak mental health and academic outcomes.


A new study, published in Child Development, investigates sleep duration for adolescents and its effects on mental health and academic achievement. The results of the study indicate that the amount of sleep necessary for optimal adolescent mental health is higher than the amount required to achieve higher academic performance and that variability in sleep duration predicts more significant mental health symptoms and lower academic achievement overall.

“Peak levels of mental health were evident among those averaging 8.75–9 hours per school night, an amount consistent with commonly promoted existing sleep guidelines. The highest level of academic performance was evident at sleep durations (7–7.5 hours) about 1 to 3 hours shorter than the guidelines,” the researchers, led by Andrew J. Fuligni, from the University of California, Los Angeles, write.

Photo Credit: CollegeDegrees360, CC BY-SA 2.0

It is widely acknowledged that sleep quality and quantity play a profound role in adolescents’ well-being. Literature suggests better sleep has a range of effects on an individual including reduced ADHD symptomology and improved overall well-being, while poor sleep has been implicated as a cause of mental health complications. Our understanding of how much sleep is needed for optimal adolescent health is mostly unknown, with national recommendations ranging from 7-11 hours per night.

“Historical analyses documenting large changes in recommendations over time have been seen by some as evidence that guidelines are based more on shared opinion than objective evidence, although others have disagreed,” the researchers write.

With adverse outcomes linked to too much and too little sleep and increased pressure placed on adolescent’s performance, there has been a call for an improved understanding of the relationship between different sleep durations and outcomes for youth.

In the present study the researches attempt to contribute to the current understanding of adolescent sleep duration, the effect sleep duration has on academic achievement and mental health, and the way variability in sleep duration can affect these outcomes. After obtaining daily check-list sleep diaries from 341 Mexica-American 9th and 10th graders from two Los Angeles areas high schools, over two separate waves, researchers examined sleep duration, variability, internalizing and externalizing behaviors, and academic achievement.

Results of the accelerated longitudinal design show as much as a 3-hour gap in students with peak mental health versus those with the highest levels of academic performance. Students with peak mental health averaged 9 hours of sleep per night, which is consistent with national guidelines, whereas their highly achieving academic peers received between 7 and 7.5 hours. Researches are careful to explain these findings do not suggest adolescents can increase their academic achievement by getting less sleep.

“It is important to note that our results suggest that reducing sleep for the sake of academic performance may result in a greater decline in mental health than the decline in academic performance resulting from increasing sleep for the sake of mental health,” Fuligni and his team explain, “the findings suggest mental health may be more sensitive to variations in sleep duration than academic achievement.”

In addition to sleep duration, researchers found sleep variability (day-to-day variability in sleep duration), “proved to be consequential for adjustment above and beyond average sleep duration,” was demonstrated by students exhibiting more internalizing and externalizing behaviors with mixed achievement scores.

While it is unclear if these findings can generalize to non Mexican-American adolescents in different contexts, or what the role puberty played in the results, this study provides evidence that even slight differences in sleep duration or variations in sleep can influence adolescent’s mental health and academic achievement.

This study adds to the growing literature that emphasizes the importance of factors, such as sleep duration and consistency, to the maintenance of mental health and well-being.

“Reductions of sleep for the sake of incremental gains in academic performance could have negative implications for mental health,” the researchers conclude. “Additionally, promoting healthy sleep behaviors for the sake of improved mental health should include efforts to minimize the variation in adolescents’ sleep duration across their daily life.”



Fuligni, A. J., Arruda, E. H., Krull, J. L., & Gonzales, N. A. (2018). Adolescent sleep duration, variability, and peak levels of achievement and mental health. Child development89(2), e18-e28. (Link)


  1. School start times are too early and it’s harmful to kids, CDC warns

    Ignorant rigid thinking people argue that all that is needed is for kids to get to bed earlier. But research shows that teenagers often can’t help staying up late.

    “In puberty, biological rhythms commonly shift so that adolescents become sleepy later at night and need to sleep later in the morning,” …

    Its proved but few people care in Americas dumb you down indoctrination centers posing as educational institutions.

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