Meditation. It is the key to falling asleep. I have TERRIBLE insomnia and so over the years I've taught myself how to relax. In essence - turning off my brain - to get to the magical *drifting off* point. Generally, I can get to sleep using that method within a half an hour and usually get a solid 3 -4 hours of rest.
When I wake up in the middle of the night, I look at the clock and make a decision based on what time it is. If it is after 4 there's really no use in trying to get back to sleep as it will take a while to get back "down" and I will end up feeling like a zombie for the rest of the day. If it is before 4, I pull myself back into a meditative state, and hope it doesn't take too long to get back to sleep.
I'm usually one of those people that can function on about 4 hours and be okay. Less than that, I get cranky. More than that, I get tired.
Naps? Forget about 'em! If I sleep during the day, my body protests and I can't sleep at night. My doctor has suggested medication but I don't want to be reliant on sleep aids so here I sit. Awake. Awake. Awake.