I can sure relate to this one. Some nights I can be exhausted and fall asleep at 10 PM but at 2:30AM I 'm for the day and feel like a zombie all day. The flip side is I don't get to sleep until 2-3AM, sleep until 6-7 AM and push myself through the day. I might add I also have chronic pain syndrome to add to being post menopausal. If I sleep from 2-8AM I feel like I can whip the world by it's tail, for about 3 hrs. LOL