It’s easy to forget the effect of a circadian rhythm that is ‘out of whack’ unless it is explained periodically. Luckily, Richard Friedman MD, in the NY Times has recently reviewed how sleep and circadian rhythm are related, as well as how incredibly important sleep is to mental health. We can’t say it better that Dr. Friedman does, but here is the review in a very recent Times article.

https://www.nytimes.com/2017/03/10/opinion/sunday/can-sleep-deprivation-cure-depression.html