When I'm stressed out and can't sleep, I do the followingly:
* Take a walk just before I'm going to bed
* When I'm in bed, I write down stuff that I finished/did well during the day, makes me feel more comfortable and satisfied.
* Write down everything I'm supposed to do the next day so that I don't wake up and my thoughts get fixated on it (I try to write down even the smallest thing like calling a buddy of mine)
* If I wake up in the middle of the night and that I keep tossing and turning but can't fall asleep again. I go up, perhaps drink a glass of milk or water, read something that isn't stressful for a couple of minutes. That normally helps me to fall asleep again since I don't get stressed out that I can't find a good position to sleep in.