Teenagers with earlier bedtimes are less likely to have depression or think about suicide, a new study reports. This adds to a growing body of research linking a lack of sleep to a higher risk of depression and other health problems in young people.
What do we know already?
Sleep is vital to our bodies, although scientists don't yet fully understand how sleep (or a lack of it) affects our health. Teenagers are one group often singled out as chronically sleep-deprived. Experts think adolescents may need as much sleep as younger children (nine or more hours a night, some say) but many don't get it because of early school start times, night-time social activities and other distractions that curtail their sleep hours.
Daytime drowsiness is an obvious consequence of missed sleep, but the effects of long-term sleep loss may go much deeper. Studies show that too little sleep may increase a young person's risk of health problems including obesity, diabetes, and high blood pressure. Research also suggests it can affect their mental state and raise their risk of depression and suicidal thoughts. However, the studies linking missed sleep with depression have had problems. In particular, they haven't been able to discount the possibility that some young people get less sleep because of depression, rather than vice versa (this is called reverse causation).
In the new study, researchers tried to get around this problem by looking at a measure of sleep not likely to be influenced by depression: the weeknight bedtimes set by teenagers' parents.
What does the new study say?
The researchers found that adolescents whose bedtimes were 10 p.m. or earlier were 24 percent less likely to have depression and 20 percent less likely to have thought about committing suicide than those whose bedtimes were midnight or later.
The study included 15,659 teenagers who'd taken part in a large US study on adolescent health issues. Interviewers asked the young people about their bedtimes, hours of sleep, and possible symptoms of depression, among other questions. The teenagers' parents were also interviewed, but separately.
The researchers found that the bedtimes reported by the teenagers were very close to the times set by their parents. And, overall, their bedtimes were closely related to their reported sleep duration, with earlier bedtimes resulting in longer sleep hours. The researchers concluded that earlier bedtimes may help protect against depression and suicidal thoughts by allowing young people to get more sleep.
How reliable are the findings?
This was a large study and it was fairly good-quality. When working out the results, the researchers factored in several things that might have influenced the young people's chance of developing depression, such as whether their parents were divorced, whether their family received state benefits, and how much they felt their parents cared about them. These adjustments make the study's findings more reliable.
However, this type of study can't show cause and effect. So it can't prove that young people were less likely to get depression or think about suicide because they had an earlier bedtime. It can show only that there may be a link.
Also, the researchers gathered their information by asking young people and their parents to describe their bedtimes and sleep hours, which isn't an entirely reliable way to collect data about sleep habits. Memories can be faulty and some people might say what they think interviewers want to hear. A better method would be for people to wear devices that measure their sleep time. However, this wouldn't be practical in a study this large.
Where does the study come from?
The study was done by researchers based in New York and was funded by grants from several research foundations in the US. It was published in a medical journal called Sleep, which is owned by the Associated Professional Sleep Societies.
What does this mean for me?
If you're a parent, this study suggests that the bedtime you set for your teenager may affect his or her risk of becoming depressed and of thinking about suicide. But we need more research to know for certain. However, we do know that getting enough sleep is important in other ways, as a well-rested teenager will be more attentive and better able to concentrate, problem-solve, and learn in school.
What should I do now?
If your teenager has a late bedtime and an early start to the school day, he or she may not be getting enough sleep. To help your child get more sleep, you might consider shifting his or her bedtime to 10 p.m. or earlier. Your child may be more alert in school - and might have a lower risk of depression, too.
Gangwisch JE, Babiss LA, Malaspina D, et al. Earlier parental set bedtimes as a protective factor against depression and suicidal ideation. Sleep. 2010: 33; 97-106.
To learn more, see our information on Depression in children and Sleep problems in children.
© BMJ Publishing Group Limited ("BMJ Group") 2010News by SoulRiser on January 13, 2010 @ 10:50 PM