I find this frusterating.
You know how every once in a while when your sleeping, you wake up after a dream.
These are usually 5-6 hours after I fall asleep initally, so I don't bother with an alarm clock.

Anyways, lots of times when I have that, I turn my light on, go wash my face with water, turn my psp on and play some games for about 15 minutes. Just enough so that I'm awake.

Then I'll get into bed, thinking about stuff constantly.
I'll get to about the stage where I start to see colors passing by my face, when (I don't realize at the time) but I doze off out of nowhere.

Any tips?