Although some people use alcohol to help themselves fall asleep, it causes sleep disruption during the night, which can lead to problem sleepiness during the day. The need for sleep may be 9 hours or more per night as a person goes through adolescence. At the same time, many teens begin to show a preference for a later bed time, which may be due to a biological change. Teens tend to stay up later but have to get up early for school, resulting in their getting much less sleep than they need. Many factors contribute to problem sleepiness in teens and young adults, but the main causes are not getting enough sleep and irregular sleep schedules.
Many adolescents have part-time jobs in addition to their classes and other activities.
High school students who work more than 20 hours per week have more problem sleepiness and may use more caffeine, nicotine, and alcohol than those who work less than 20 hours per week or not at all. Most shift workers get less sleep over 24 hours than day workers. Sleep loss is greatest for night shift workers, those who work early morning shifts, and female shift workers with children at home. The human sleep-wake system is designed to prepare the body and mind for sleep at night and wakefulness during the day. These natural rhythms make it difficult to sleep during daylight hours and to stay awake during the night hours, even in people who are well rested.