Ridiculously late, in fact -- been thinking about it, and have decided it's because I don't have any reason to get up early, even though I do get up at 7AM if not earlier on the kids' school days.
I remember when I lived in Massachusetts, I might stay up till midnight, but usually didn't last that long, usually I'd turn in around 11PM. I was getting up at 6:30 or 6AM to do morning rituals and the 30-45 minute commute to work, which would typically start at 8AM. I had an 8AM to 6PM work day, typically -- hours that minimized the commute, mostly, and made long lunches guilt-free. I had that routine for years. What happened?
I don't think I can blame the babies, although they did disrupt sleep quite a bit during their early months. But since DS2 is 7 years old, I don't think that's relevant anymore.
I think it's not-working. When I know I'm going to be subbing, I'm good about getting a decent amount of sleep the night before. If I were working full time, I'd get back into that groove of going to sleep at a normal time. But since I'm not working full time, I have apparently given myself license to stay up till whenever. What difference does it make? (Rhetorical question -- isn't it obvious?)
I got laid off from Oracle more than nine years ago, and I still haven't fully recovered. It's especially ridiculous because the list of my involvements is not small, and I could really use more sleep. It's just because my schedule is so flexible that I let regular sleeping hours go.
Lately, it doesn't help that the time of day my stomach feels best is after midnight. I'm not supposed to eat before going to bed but feeling hungry and actually being able to eat? That's something I enjoy.