Experts say teenagers require eight-and-a-half to nine-and-a-quarter hours of sleep per day. But, reports The Early Show medical correspondent Dr. Emily Senay, a study in this week's journal Pediatrics reveals the impact of early school start times on teenage sleep patterns.
A survey of students from 12 to 15-years-old found they lost an average of two hours of sleep on school nights because they had to get up earlier. The study also found poorer performance on alertness tests in the morning compared to the afternoon. The students reported being wearier and less alert in the morning.
Researchers say the early start and loss of sleep could be hampering student performance in school.
The findings, Senay says, add to the growing body of evidence about the negative effect of sleep deprivation on teenagers. Other studies have found that it's normal for adolescents to go to sleep later at night and wake up later in the day than adults.
People getting less sleep than they need are susceptible to a variety of problems, Senay says. They are less alert and attentive, and likely to experience mood swings. A chronic shortage of sleep is linked to a greater likelihood of starting to smoke or to be involved in car crashes.
There are efforts under way to delay school and standardized test start times, and some school districts around the country have begun making changes. And the researchers say this new evidence will probably be enough to change everybody's mind. The researchers add that, in the meantime, teens should be taught about the importance of getting enough sleep.