Excersice. I know, it sounds trite. But working out has helped me sleep more soundly despite getting less sleep. I have a few weights in my basement and when my kid is sleeping, I go downstairs and lift heavily. Especially leg workouts, your legs are a huge portion of your body and getting those muscles working is great. It usually takes me ~20 minutes to workup a sweat. Before I had a child I used to try cardio for longer periods of time. But I am more satisfied with short, difficult strength workouts.