Are You Sleep Deprived?

What time do you hit the sack? If it's any time after 10 p.m., your lack of sleep might have something to do with your mood.

Columbia University Medical Center surveyed 15,659 teenagers and found that teens who stayed up until midnight or later were 42 percent more likely to be depressed than those who went to bed by 10.

"We feel like we can eat into our sleep time, but we pay for it in many different ways," researcher James Gangwisch says.