All true and good stuff -- But I think the OP is pointing out that being a Night Owl is probably confounded (majorly) with a significant range of other health a

All true and good stuff -- But I think the OP is pointing out that being a Night Owl is probably confounded (majorly) with a significant range of other health and lifestyle factors. This is always a major challenge in these types of studies. It's useful research - but it often ends up as a news headline "doing X is a factor in Death." Which is often misleading.