During the transition to adolescence, sleep patterns change. It becomes lighter, and the teenager's internal clock tends to shift, with a later onset of sleep and wakefulness. Nevertheless, teenagers still need a lot of sleep: the recommended sleep duration is 8 to 10 hours. Between the ages of 12 and 18, during the school year, a teenager misses an average of 1 to 2 hours of sleep per night, which equates to a lost night's sleep at the end of the week. Sleep-deprived teenagers are more irritable, more sensitive to stress, may perform less well at school and experience sleepy episodes during the day. To remedy this, an effective strategy known as chronotherapy, which takes place over the course of a week, gradually shifts the teenager's sleeping hours. 

For further information, we recommend that you consult :

- Institut national du Sommeil et de la Vigilance website
- Morphée network website (health network dedicated to the management of chronic sleep disorders)
- Ameli website
- The website of ANSES, the French Agency for Food, Environmental and Occupational Health and Safety (Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail)
- The Santé Publique France website, and its documents on sleep