Ok non-24 is this. I have a 26 hour day that cannot be changed 18 hours awake 8 hours of sleep. so basically my sleeping schedule for a week goes like this.
Sleep Wake
Monday 9pm 5am
Tuesday 11pm 7am
Wednesday 1am 9am
Thursday 3am 11am
Friday 5am 1pm
It's basically inconsistent insomnia that occurs at different parts of the day. Now if your daily life doesn't fit in with that sleep schedule some nights you'll be able to sleep at night other nights there is no chance even with sleeping pills to fall asleep. It's a rare one even my doctor doesn't have a clue what caused it.
Oh as a side bonus to this one it is often misdiagnosed as bipolar, depression, and a whole slew of other stuff.
http://en.wikipedia....p-wake_disorder
DSPD is delayed sleep-phase disorder is pretty much like jet lag where your body clock is setup to go to sleep later then normal
Basically you want to go to bed at 9 pm but can't because your body is like screw you your bedtime starts at 3 am get used to it. At least with this you can trick your body clock in to fixing itself with a few options.
http://en.wikipedia...._phase_disorder