June 9 (HealthDay News) -- Teens whose parents pack them off to bed at 10 p.m. are less apt to become depressed or have suicidal thoughts than their peers who stay up much later, recent research shows.
"This study bolsters the argument that a lack of sleep can cause depression," said study author James Gangwisch, an assistant professor of psychiatry at Columbia University Medical Center in New York City. "Teens with earlier parental-mandated bedtimes were less likely to suffer from depression and suicidal thoughts."
Gangwisch was to present the findings Tuesday at the Associated Professional Sleep Societies annual meeting, in Seattle.
The study stemmed from data on more than 15,000 adolescents who participated in the National Longitudinal Study of Adolescent Health.
The researchers found that 1,143 of the teens were depressed and 2,038 had suicidal ideation, the term clinicians use to describe suicidal thinking. Dr. Jonathan Pletcher, an adolescent medicine specialist from Children's Hospital of Pittsburgh, pointed out that suicidal thoughts are common in teenagers, which is why the study included more teens with suicidal thoughts than depressed adolescents.
"A lot of teens have suicidal thoughts, but there's a big difference between suicidal ideation and being suicidal," Pletcher said.
When Gangwisch and his research team looked at the relationship of depression and suicidal thoughts to parental-mandated bedtimes, they found a clear correlation.
Teens whose parents insist on 10 p.m. or sooner for lights out were 25 percent less likely to be depressed and 20 percent less likely to have suicidal thoughts, compared with kids who hit the sack at midnight or later.
Gangwisch said he adjusted the data to account for numerous factors, including parental connectedness and the age of the teens, because older teens probably would have later bedtimes. After controlling for these factors, he said, it was clear that a lack of sleep was to blame for the increased risk of depression and suicidal thoughts.
"Kids that have to go to bed earlier are getting more sleep," he said.
Pletcher said it's likely that a combination of factors accounted for the increased risk. "There's a bi-directional relationship between depression and sleep," he said. "Teens who get less sleep may be more anxious and more likely to feel badly. But, I think this study's findings also speak to a connection between the teen and their parents and their ability to work together."
Both Gangwisch and Pletcher agreed that most teens need at least eight to nine hours of sleep a night, and said that parents might underestimate their teen's need for sleep.
"Getting adequate sleep is a huge priority," said Pletcher. Besides increasing the risk for depression and suicidal thoughts, a lack of sleep can affect a child's focus and learning, he said. And Gangwisch said that a dearth of sleep is also associated with obesity and type 2 diabetes.
Pletcher said that teens who don't get enough sleep may also be more impulsive.
"Don't underestimate how a lack of adequate sleep can affect everything from mood to behavior," he advised.
SOURCES: James E. Gangwisch, Ph.D., assistant professor, division of cognitive neuroscience, Department of Psychiatry, Columbia University Medical Center, New York City; Jonathan Pletcher, M.D., adolescent medicine specialist, Children's Hospital of Pittsburgh; June 9, 2009, presentation, Associated Professional Sleep Societies annual meeting, Seattle