Exercise, reading, green tea, lack of coffee and tea, and not eating much. Not eating much except for something nutritious but low in calories like vegetable soup gets me into a calmer, more stable state, probably because I lack the rush of energy to care and I have a certain attitude towards it. I think it's why some religions advocate periods of fasting to clear the mind. It also makes me wake up early without an alarm, with this empty, almost romantic feeling.
I don't think green tea chemically facilitates sleep, but it's supposed to be good for you somehow and I feel something hot, sugarless and (mostly) lacking in caffeine matches bedtime.
If you feel like experimenting a little, if you haven't already, cut out sugar (apart from a little fruit), caffeine, and most other simple carbohydrates for a few days. Eat until 70 percent full, as the Japanese say. Go for a run or do some other exercises.