A recently published study about the relationship between sleep time and depression in teens has many people confused. It was a co-relational study and thus does not confirm causality. So it is not possible to conclude that going to bed late causes depression in adolescents. On the other hand, the study does bring the spotlight back on the well known scientifically but less well appreciated complex relationship between sleep and depression in teens.
We have known for a long time that sleep is disturbed in teen depression. We have also known for a long time that the usual sleep architecture (that is how the different stages of sleep happen during the night) is disturbed in teen depression. We also know that some teens who get depressed show subtle changes in their sleep architecture before they get depressed. Many years ago my research team reported those findings and we also showed that there were abnormalities in hormone secretion at night in depressed teens. And, we know that forced waking early in the morning may improve symptoms in depression. So there is clearly something happening in how the brain controls mood and how it controls sleep.
But, it is simplistic and wrong to assume that setting late bedtimes for teen’s causes depression. This is not the case and it would be foolish to try to tell parents and teens that going to sleep before midnight is protective against depression. However, there is much for us to learn about sleep and depression in teenagers. And there is a growing interest amongst researchers in this area. So stay tuned!