Study says Going to Sleep on Time = Less Depression

By Dave

A new study shows that teens who go to bed on time are less likely to suffer from depression:

Of 15,500 12 to 18-year-olds studied, those who went to bed after midnight were 24% more likely to have depression than those who went before 2200.And those who slept fewer than five hours a night had a 71% higher risk of depression than those who slept eight hours, the journal Sleep reports.

My only thought is that I wonder if the study is actually capturing the effect of sleep on depression, or if the results are being biased by other factors. It could be just as likely that teens who are up late are different in other ways than kids who aren't. As an example maybe it's that teens who go to bed early are not engaged in the same activities that the teens who are up past midnight are involved in. Not to stereotype too much, since I was a kid often up past midnight, but it could be that teens who only getting 5 hours of sleep are more likely to be at parties where there is more underage drinking, or drug use, or teen romance, or any number of teen dramas that could be correlated with depression. Or maybe they are dealing with family illness, or broken homes or any number of things that would cause one to get less than a full night's sleep.

I guess I'm just thinking that the study, or at least the report on the study, doesn't do much to persuade us that sleep is really the factor linked to depression. It seems more likely to me that sleep is a proxy for some other factor.

Any thoughts?