I put 4-6 but sometimes it's none and sometimes (oh blessed joy) it's more like 10+.
As far as I can tell I'm non-24 and have been since I was a teenager. Left to myself I'll eventually "go through" and miss a night of sleep and get to bed in the day instead. Unfortunately the effect of my sleep phase seems to have been magnified by having to be up to care for the kids. Now that trigger has set things off I'm completely messed up.
The nights when it's none I can't sleep, feel awake and try to work (on the computer, though I'm fatigued and have done a days "work" already) and get to the point I can get to bed but the kids start waking up and so I'm into getting them up and ready for school. This is really hard.
Recently it's been the worst it has been I've had about 8 hours sleep in 5 days about a fortnight ago and had to look after the kids in the day. A real nightmare.
Alcohol usually will help me get to sleep earlier but I'm really concerned about becoming alcoholic. I guess drugs would probably do it but then I need to be up to attend to the kids so if they knock me out that would be no good.
TL;DR argh, I can't sleep.
Edit: and exercise can't hurt either. It only takes 30 minutes to go for a good jog and is something doctors always recommend.
(I know it might sound overengineered, but hey, it's also fun! ;))