Exercising. More specifically aerobic exercising. High and low intensity both work, but you have to do enough to properly exhaust yourself, just 15 minutes of w

Exercising. More specifically aerobic exercising. High and low intensity both work, but you have to do enough to properly exhaust yourself, just 15 minutes of walking is not enough. And not doing anything too exciting or demanding 2-3 hours before going to sleep. Maybe you just haven't done enough or not consistently enough.