[gwern]

> assuming that you will still have a balanced social life, i have not found any conclusive research that proves it is harmful to sleep at an irregular hour.

Well, depending on what you mean by that. For example, go to sleep with the sun shining on you, and I guarantee you you will have worse sleep from lack of melatonin secretion!

In a related point, while researching links between melatonin & depression for http://www.gwern.net/Melatonin#fn5 I noticed that Lewy et al 2006's SAD sufferers had normal total amounts of sleep, but they all seem to suffer delays or advances in their sleep schedule compared to normal people, which is suggestive...

[ga0bi]

you're correct; if you go to bed with the sun shining on you, not only will you have uncomfortable sleep, you will also have an extremely weak immune system and will be more prone to sickness (due to the lack of melatonin). further points are discussed in the bullet lists.

the best environment to sleep in would be a dim/dark room. personally, I'm sleeping in the living room, so I make sure that the blinds are properly blocking potential sunlight to ensure uninterrupted sleep.