I'm a night owl and I think I know what's going on here, at least as far as I'm concerned. It is that every so often I indulge in too much coffee, booze, etc,

I'm a night owl and I think I know what's going on here, at least as far as I'm concerned. It is that every so often I indulge in too much coffee, booze, etc, and this pushes back bedtime by an hour or two. Or I get excited about something new like a book or a video game. Since the night time is quiet and I am undisturbed by others, I like it, and I don't bother to correct it. Note that merely giving up coffee, as the doctor in the article recommended, wouldn't help. It is the irregular 'binges' that push our body clocks. The extreme case would be a hard drug user who occasionally parties for 2 nights in a row. Of course eventually some social obligation or appointment causes me to have to get up at a normal hour one morning and then the process resets and slowly advances all over again. Two comments about this: (1) society may be correct to judge me, because there are addictions involved and they can be harmful. (2) it's unhealthy because when one eats during a period which was recently 'sleep time' the body doesn't digest the food so well. The heart doesn't seem to like it, and I think I read that LDL cholesterol is elevated. This is one reason why night shift workers pay a price in terms of health.