According to a research led by James Gangwisch, a professor of psychiatry at New York's Columbia University Medical Center, late nights not only deprive the teenagers of sleep, but also make them more prone to depression and suicidal thoughts.

The study, which suggested that early bedtimes may be beneficial for teenagers, found that while the American Academy of Sleep Medicine has recommended at least nine hours of sleep for adolescents, the average sleep time for most teenagers is a little less than eight hours.

For the study, published in the journal 'Sleep,' the research team analyzed comprehensive data of 15,659 US students, studying in Grades 7 to 12 between 1994 and 1996, and their parents. Out of the participating teens, seven percent reported depression, while 13 percent said they seriously contemplated suicide in the preceding one year - most of these beings girls or older teenagers.

Specifically speaking, the researchers found that there were 24 percent more chances of depression and 20 percent more likelihood of suicide contemplation by teens who were allowed to sleep after midnight, vis-à-vis their counterparts who went to bed at or before 10 p. m.

Commenting on the findings of the study, which was funded by the Robert Wood Johnson Health and Society Scholars Program at Columbia, Gangwisch said: "Our results strengthen the argument that lack of sleep can cause depression as opposed to simply being a symptom of depression."