Until I retired I would be up half the night fretting about deadlines and spreadsheets. Even when I was bone weary I'd toss and turn for an hour or so before I finally nodded off, then wake up with a start again two hours later worrying about things I hadn't done that day. And so it continued till it was 5.45 and time to get ready for work, or until I gave up, got up and started working on my computer at any time from about 4.
Now, I read for twenty minutes or so, switch off the light, put my head on the pillow, count my blessings, smile sweetly and nod off. Seven or eight hours later I wake up, still smiling. Ah, retirement....... 