You could try exercise such as jogging. Id suggest it more during the day though. That way fatigue builds on your body a bit slower. Personally I cant run to make me tired cus running increases my energy for another hour and then Im just laying there thinking about doing more, but thats me, maybe jogging at night would benefit you though, just have to experiment. But when I have insomnia I usually read. If it doesnt put me right out then at least my mind is a bit rested. You could also try meditation. My brother used to meditate for like one or two hours at night and then attack the whole day as if he had a full nights rest. It does do wonders to the mind and body.