I think you could begin gradually with some exercise. Exercise will not only help your brain but it should also help you sleep. Pick something that works for you: walking, running, cycling, yoga, whatever. Just pick something that works your heart and pumps your blood. Your sleep will also be helped by lowering stress. Worry is a big stressor.
I remember learning in a Franklin Covey time management course that there are two walls in our lives. There is the wall of control and the wall of no control. We get into trouble when we try to control the things on the wall of no control. I guess I’m saying, “let go, Luke.”