Sleep is a risk factor (well, lack of it is...)

Ten years ago I wrote a piece lamenting the lack of research into the epidemiology of sleep. So of course I now have to commend this paper.  The main limitation is that the study group were volunteers followed by fairly high loss / wastage: given that this is a sample of police officers, the fact that almost 80% were overweight or obese suggests substantial selection bias (or maybe things are a lot worse in the USA than I thought...).