Sorry you&#x27;ll have to Google it. I read almost everything I find on sleep and I encountered this quite a lot, it was even said to me by my doctor and a psychiatrist.<p>A few days ago there was something on HN about how people that slept late on week ends had a shorter lifespan than other, it shouldn&#x27;t be hard to find.<p>Now for my sample of one : I&#x27;m subject to SAD (seasonal affective disorder) and common depression too but when I manage to stick to a strict wake up time (6AM at the moment) my quality of life is greatly enhanced. And this despite that I&#x27;m more an evening (even night) person.