The Centers for Disease Control and Prevention suggests that adolescents get eight and a half hours to nine and a half hours of sleep a night. However, only about 15 percent of all American teenagers actually get that much on a regular basis, and many get less than six and a half hours a night. What is it about teenagers’ sleep cycles? Compared to adults, their biological clocks are shifted. As part of normal brain development, at around ages 10 to 12, the biological clock shifts forward, creating a “no sleep” zone around 9 or 10 o’clock at night, just when parents are starting to feel drowsy. One reason is that melatonin, a hormone critical to inducing sleep, is released two hours later at night in a teenager’s brain than it is in an adult’s. It also stays in the teenager’s system longer, which is why it’s so hard to wake your high schooler up in the morning. Adults, on the other hand, have almost no melatonin in their system when they wake up and therefore don’t have the same groggy feeling.

Sleep is critical to learning and memory. Much research has shown that synaptic plasticity, needed for memory, is negatively affected by sleep deprivation. In addition, for memories that have already just been created, sleep appears to be a period for consolidating memories to help induce their permanence. So teens are at risk for being sleep deprived due to the “adult” schedule that starts the day at an unnaturally early time for them, and once sleep deprived, their brains are not as able to build new memories as well as when they are well rested. All not great.

Recent research shows that melatonin is not only pretty critical for inducing sleep, but it is also factor for synaptic plasticity and memory formation.  Importantly, melatonin levels fall during sleep deprivation. Melatonin can set in motion a cascade of proteins that help maintain memory abilities.  Recently researchers have been trying to harness that pathway to look for drugs that can mimic proteins turned on by melatonin. However, that is still a ways off, and for now, the best approach is to just GET SOME SLEEP!! 

About the Author

Frances E. Jensen, M.D.

Frances E. Jensen, M.D., is a professor of neurology and the chair of the neurology department at the Perelman School of Medicine, University of Pennsylvania.

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