Columbia researchers have found new evidence that inadequate sleep can lead to depression and suicidal thoughts in adolescents. The study of nearly 16,000 teenagers in grades 7 to 12 found that adolescents with bedtimes set at midnight or later were 24 percent more likely to suffer from depression than those with bedtimes of 10 p.m. or earlier. Teenagers with later bedtimes also were 20 percent more likely to have suicidal thoughts. The study was published in the January issue of the journal Sleep.
Depression and poor sleep often go hand in hand, but sleep difficulties are usually seen as a symptom of depression, not a cause, says James Gangwisch, Ph.D., assistant professor of psychiatry and lead investigator of the study.
To see if sleep deprivation can lead to depression, researchers would have to alter teenagers’ sleep schedules and record the results, so Dr. Gangwisch did the next best thing. He gathered data from a “natural experiment” – what happened when teenagers had their bedtimes imposed by their parents. Data on bedtime and depression came from the National Longitudinal Study of Adolescent Health, conducted between 1994 and 1996.
The reasons why sleep deprivation may lead to depression, though, are still unclear. Dr. Gangwisch says moodiness from a lack of sleep may interfere with a teenager’s ability to cope with daily stress or impair relationships with friends and family. Suicidal thoughts may increase due to the effects of insufficient sleep on judgment, aggression, and impulse control.