Just One More Snooze

Updated: Apr 21, 2020

Author: Diane Zhou (Torrey Pines High School)

Recently, California passed a bill mandating later school start times in middle and high schools. It’s safe to say this excited many people, especially the students.

But what does the research say about later start times?

Generally speaking, today’s teens do not get enough sleep, leading to adverse effects on their daily lives. Almost 70% of teens get less than seven hours of sleep when the CDC recommends eight to ten hours a night. Students who reported an insufficient amount of sleep were more likely to engage in risky, injury-prone behaviors, e.g. not wearing helmets or seatbelts, DUIs, texting while driving, than their well-rested counterparts. [1] Students were also more likely to be physically and mentally unhealthy, resulting in poorer performance in school and in some extreme cases, obesity, metabolic dysfunction, depressive symptoms, and mental health problems. [2] Although the effects mentioned above are not always unique to insufficient sleep, studies have shown that sleep-deprived students are more likely to make risky decisions and disregard the dangerous consequences. [1]

So why is there such a drastic impact due to insufficient sleep? Because teenagers are going through puberty, their natural circadian rhythms are delayed, unlike adults’. Our circadian rhythms, or our 24-hour sleep-wake cycle, are essential to how aware, concentrated, or tired we are during the day. A delayed cycle means that adolescents’ energy levels will rise and fall in a cycle a couple hours behind the typical adult’s. Essentially, a teen could be sleepy, lethargic, and unaware at the same time an adult is alert and energized. On top of a delayed rhythm, there is now evidence that adolescent circadian clocks are less sensitive to light in the morning, which means it is actually harder for teens to wake up earlier in the morning when there is no light. Additionally, research has shown that these delayed rhythms allow adolescents to stay awake later into the night. [3] So, it’s not exactly the teen’s fault they can’t wake up in the morning or fall asleep at night. Having an earlier starting schedule works against most teens’ natural clocks and leads to insufficient sleep.

Another interesting aspect is the role of melatonin--a hormone controlling your sleep and wake cycles. It goes hand in hand with your circadian clock. Evidence shows teens experience delayed patterns of melatonin, which causes the aforementioned delayed circadian rhythm. Your body wants to stay up later and it may even be hard for you to fall asleep before 11 pm. [2]

With later school start times, these negative effects started to recede. Due to longer sleep hours, students became less sleepy, more alert, and had better academic performance. [3] Depressive symptoms and irritability were also reduced. [3]

All in all, the research outlines many of the benefits of delayed school start times. (And the next time you’re arguing with your parents about sleeping later, know that science is on your side.)


[1] Wheaton, Anne G, et al. “Sleep Duration and Injury-Related Risk Behaviors Among High School Students - United States, 2007–2013.” Centers for Disease Control and Prevention, 25 Aug. 2017,

[2] Watson, Nathaniel F., et al. “Delaying Middle School and High School Start Times Promotes Student Health and Performance: An American Academy of Sleep Medicine Position Statement.” Journal of Clinical Sleep Medicine, American Academy of Sleep Medicine, 15 Apr. 2017,

[3] Dunster, Gideon P., et al. “Sleepmore in Seattle: Later School Start Times Are Associated with More Sleep and Better Performance in High School Students.” Science Advances, American Association for the Advancement of Science, 1 Dec. 2018,

Edited by Jade Nam (Torrey Pines High School)

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