Ask HN: Studies on success vs. hours of work and sleep?

Does anyone know of any studies done on entrepreneurs and how much sleep they get and/or how many hours they work each day, as well as how much success they achieved?

I frequently see anecdotal evidence on here that working more / less hours or getting more / less sleep will make you more successful but it would be nice to have some scientific basis behind these claims rather than just stories of "this is what worked for me".