[nottorp]

> I prefer to stay up into the night and wake up around 12:00, but I vary my sleeping hours by up to 4 hours or so. I go to sleep when I feel like it, and don't feel much discomfort by falling asleep at different times.

Yep. Exactly the same here. I tend to wake up 7-9 hours after I go to sleep (usually between 00-04:00) no matter when that happens. With very rare occurences of two part sleep. No side effects by 45, but I do exercise.

Come to think of it, I may get two part sleep more often than I think, because I do wake up during the sleep period. But most of the time I ignore it and fall asleep again in a couple minutes.