A new poll from the National Sleep Foundation has found that half of Americans report one symptom of insomnia at least several nights a week. Two thirds of Americans say they have driven while drowsy, and only a quarter sleep the recommended eight hours a day. But sleep problems are especially common in teenagers.
Researchers say the average teenager needs more than nine hours of sleep a night. But most American teenagers are sleeping only seven hours on school nights.
"Teenagers really are among the most sleep-deprived people in this country," says Ms. Carskadon.
Mary Carskadon conducts sleep research at Brown University Medical School in Providence, Rhode Island. Ms. Carskadon says that biological changes during puberty affect an adolescent's internal sleep-wake clock. Teenagers produce melatonin -- the hormone that helps trigger sleep -- hours later than when they were children.
As a result, most teenagers are not ready to sleep before 11 o'clock at night. But they usually need to get to school by 7:30 or earlier in the morning, when classes begin.
Ms. Carskadon says that night after night, teenagers are building sleep deficits that dampen their ability to perform and react properly. Sleep deprivation also affects a teenager's mood.
"A lot of teenagers who are sad and tired and fatigued are now taking medication for depression. That may not be depression. It may simply be inadequate sleep," says Ms. Carskadon.
Some school districts have set later starting times to allow students to sleep more in the morning.
High schools in Minneapolis pushed the start of classes from 7:15 to 8:30 in the morning. With more sleep, researchers say the students showed fewer signs of depression and their school attendance improved.
Kyla Wahlstrom is an education expert at the University of Minnesota in Minneapolis.
"The impact has been remarkable. And the parents have said their kids are easier to live with. The schools are saying their students are more ready for learning," says Ms. Wahlstrom.
Experts say teenagers aren't the only ones who need more sleep--many adults also carry a significant sleep debt. Helene Emsellem is head of the Center for Sleep and Wake Disorders in Chevy Chase, Maryland.
"One of the most important things is taking a little bit of time to wind down between the craziness of our day, getting home, getting dinner prepared, getting the kids taken care of and then allowing a little bit of wind down time for ourselves," says Dr. Emsellem.
Researchers say that with most Americans reporting difficulty falling asleep or frequent waking, more people should discuss their problems with a doctor.