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The Jet Lag of Adolescence

May 20, 2022

Teenagers are notorious for their capacity to sleep late into the day. This is a bona fide natural phenomenon and doesn’t necessarily mean teens are lazy, it just means they are different. Two key factors seem to drive these changes in the adolescent sleep cycle1:

  1. Puberty delays intrinsic melatonin release by 1-3 hours, resulting in a significant shift in circadian rhythms during adolescence.
  2. The “homeostatic drive” for sleep describes the need for sleep that accumulates while we are awake (i.e., the longer we stay awake, the more tired we get).

This combination often leads to a pattern of sleepy mornings and late-night wakefulness in this age group. 

To accommodate these changes in the adolescent biological clock, delays in school start times have been proposed, debated, and enacted at state and local levels. In the current issue of Pediatrics, Yip and co-authors examined the effects of school start times on a variety of sleep-related and developmental outcomes in middle- and high-school students (10.1542/peds.2021-054068). Their systematic review and meta-analysis found small, but significant, effects of school start times on sleep quality and duration, as well as overall developmental outcomes. Given the growing recognition of the critical role sleep plays in the health and development of children and adolescents, these findings should help inform future policy discussions on this topic.

When examining school schedules, it should be recognized that teenagers are essentially living in a different time zone than the rest of us. Daily schedules that fail to accommodate these biologically driven sleep patterns force adolescents to function in a permanent state of “jet lag,” as if they have just flown several time zones to the east. Adolescence is challenging enough without the added physiologic strain of working against one’s intrinsic time clock. Yip and co-authors bring much needed objective data regarding the potential benefits of accommodating this developmental phenomenon by delaying school start times. The average high school start time in the US is 8 am.2  When considering sleep-related factors and developmental outcomes, this paper suggests sometime between 8:30-8:59 am may be a better option. 


  1. Carskadon MA. Sleep in adolescents: the perfect storm. Pediatr Clin North Am. Jun 2011;58(3):637-47. doi:10.1016/j.pcl.2011.03.003
  2. Start Times in U.S. Public High Schools (U.S. Dept of Education) (2020). Accessed March 17, 2022.
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