Breakfast scenes, eyes half-closed, phone in hand: for many families, the tired teenager waking up has become the norm. Behind these difficult mornings lies a simple question for parents and doctors alike, about the sleep of middle and high school students.
Yet doctors have been talking about this problem for over a century. Numerous studies have linked shortened nights to overexcitement, mental health problems, more accidents and academic difficulties. Recent major surveys now show that adolescents are sleeping even less than before.
Adolescent sleep: 8 to 10 hours recommended each night
To answer the question “how many hours of sleep for a teenager”, specialists converge: between 8 and 10 hourswith 9 hours ideal between 14 and 17 years old. Below 8 hours, the adolescent lives in daily deprivation. Deep slow-wave sleep, essential for physical recovery and the secretion of growth hormone, like paradoxical sleep, key to memory and emotions, is cut short.
At puberty, the biological clock shifts: melatonin, the sleep hormone, is released later. The teenager becomes a “night owl”, without being able to get up later during class periods. Late naps, screens rich in blue light and evening sports delay falling asleep and increase sleep debt.
How many hours do teenagers really sleep during the week?
In France, EnCLASS surveys find among middle school students around 8 hours 16 minutes of sleep on nights with classes, but a growing proportion falls below 7 hours. Between the ages of 12 and 18, during school, specialists estimate that a teenager lacks on average 1 to 2 hours of sleep per night, which often reduces their night to around 7 hours. In high school, the average falls to 7:19 a.m. on weekdays, and almost half of the students report sleeping “around 7 hours”, while around 30% fall below 7 hours. In practice, between homework, commuting and evening screens, a large part of high school students therefore work at only 6 to 7 hours of sleep. Late nights at the weekend, with more than two hours difference for 40% of adolescents, reflect this accumulated “social jet lag”.
More than half sleep less than 5 hours per night!
In the United States, according to a recent study led by T. Greg Rhee, psychiatric epidemiologist at the University of Connecticut School of Medicine, more than 50% of adolescents report sleeping less than 5 hours per nighta higher proportion than in all previous surveys. Sleeping less than 5 hours per night is considered a significant lack of sleep and is associated with emotional regulation problems such as anxiety and depression, poor academic performance or delayed neurocognitive development, and an increased risk of obesity and diabetes. The percentage of adolescents getting enough sleep, eight hours or more per night, has fallen from more than 30% in 2007 to less than 25% in 2023.
“These trends highlight the need for population-wide interventions among adolescents. For example, a later class start time may promote longer sleep, which could improve mental health and academic engagement.”said Rhee and his colleagues.
What happens when a teenager only sleeps 6 to 7 hours?
For a teenager’s brain, these too-short nights are not trivial. An Inserm team showed, in 177 14-year-old students, that sleeping less than 7 hours during the week and going to bed very late on the weekend were accompanied by smaller volumes of gray matter in the areas of attention and concentration. “The most significant result of our study is certainly the one which shows that the later adolescents go to bed on weekends, the more their gray matter volume is reduced.” explains Jean Luc Martinot, Inserm research director, quoted by Inserm.