(HealthDay News) -- Research shows that teen and pre-teen girls need more than nine hours of sleep a night.
Without it, they become cranky, don't do as well at school, and may feel depressed.
Natural changes in the body may keep teenage girls wide awake long after they're supposed to be asleep, according to Girl Power, a national public education campaign sponsored by the U.S. Department of Health and Human Services.
So what can teen girls do to make it easier to fall asleep? Girl Power suggests keeping regular bedtime hours, relaxing before going to bed (avoid reading scary novels), playing sports in the afternoon but not right before bed, and avoiding foods and drinks that contain caffeine.