It's most likely associated with you retiring.... try to be more active in the daytime. A good 1 hour walk or 2 half hour walks is a great thing to do. Or join an exercise class that meets daily....they have them for seniors. Or if you like to swim, try going to an open swim pool in your area. The YMCA has them. My mom had an exercise bike that she rode for 15-20 minutes a day. Enjoy retirement and maybe you don't mind waking up at 3am and not being able to fall back to sleep. That's okay. But it would drive me bonkers! I guess I'd try staying up later maybe. Take care!