Teens ages 14 to 18 who get fewer than 8 hours of sleep on school nights—some 70 percent of U.S. high school students—may be more likely to engage in risky behavior, according to a new study released Monday by the Centers for Disease Control.
The study's authors examined the 2007 national Youth Risk Behavior survey and found that students who averaged less than a full night's sleep were more likely to use drugs, drink alcohol, be depressed, and be less physically active than well-rested students.
Lela McKnight-Eily, the study's lead author, says that it's hard to tell if students are engaging in risky behavior because they're not getting sufficient sleep, or if they're not getting sufficient sleep because they're engaging in risky behavior. She says a change in the brain's chemistry that occurs during puberty causes the body's internal clock, or circadian rhythm, to be knocked off track, causing irregular sleep patterns in many teens.
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"There's not a direction implied by this study. What we do know is that during the period of adolescence, there's a change in biology that causes a two-hour delay in your circadian rhythm," she says. "Even if they're not out doing these risk[y] behaviors, they're going to want to be out later, they're going to want to wake up later."
McKnight-Eily says that broad, societal changes are causing teens today to get less sleep than in the past. "The TV doesn't turn off anymore; they can text; they can use computers," she says. "I think there's a combination of factors going on."
She says that being up late surfing the Internet or watching TV when trying to fall asleep can cause restless nights. She adds that it's important for teens to have a somewhat regular sleep schedule.
Length of sleep seemed to have the greatest correlation with the following health-risk behaviors:
|Risk behavior||Rate among insufficient sleepers||Rate among sufficient sleepers|
|Seriously considered attempting suicide||17%||10%|
|Feelings of sadness or hopelessness||31%||22%|
|Currently sexually active||39%||28%|
Insufficient sleepers average fewer than eight hours of sleep per night; sufficient sleepers average at least eight hours of sleep per night.