I’ve found that it boils down to either excess energy not burned off, or not enough calories to slow the mind down yet. So if my mind is racing a bit I get up, eat something small and light on the stomach like a banana or cereal in the dark without tv or the phone. I use some of this time to meditate as well.

Also getting enough sun or vitamin d helps. Trying to burn off as much energy before my mind has a chance to race before the end of the evening.