A new study in the Jan 1, 2010 issue of the journal Sleep found teens who slept 5 or fewer hours a day regularly were 71 percent more likely to suffer depression and 48 percent more likely to think of suicide compared to those who had sufficient sleep.

The study showed teenagers who set bedtimes around midnight or later were 24 percent more likely to experience depression and 20 percent more likely to have thoughts of suicide compared to those going to bed before 10 p m or earlier.

James E. Gangwisch, PhD, co-author of the study, of Columbia University Medical Center in New York was cited as saying the inadequate sleep is a risk factor for depression. The study involved 15,659 adolescents and their parents who participated in the National Longitudinal Study of Adolescent Health between 1994 and 1996.

The researchers said teenagers need 9 hours of sleep each day. The study found teens on average slept 7 hours and 53 minutes. This study suggests that inadequate sleep can result in depression.  However, early studies suggest otherwise, that is, depression the moody disorder can lead to the inability of sleep or insomnia.

Short sleep, inadequate sleep, disturbed sleep, sleep deficiency or lack of sufficient sleep have been found to cause a variety of problems including high risk of incidents, low work productivity and increased fatigue among other things, according to a recent report. The report was authored by Ohlmann KK and O'Sullivan MI and published in the Sept 2009 issue of AAOHN journal: official journal of the American Association of Occupational Health Nurses.

Depression symptoms include feeling sad, anxious, irritable or empty, hopeless, worthless, fatigue, loss of interest, increased or reduced need for sleep and thoughts of death or suicides or attempting suicide. Depression has been linked to vitamin D deficiency which is common in teenagers.  Those who are concerned may consider using some supplement of this sunshine vitamin.