I find, as I get older, I don't need as much sleep. Sometimes I go to bed in the early hours, 2-3am, sometimes later. Other times I'm in bed before midnight, sleep for a couple of hours, wake up, then can't fall back asleep, so I get up have a cup of tea, have a look on here for a while then back to bed.
I don't need more than 4-5 hours sleep, I've only been this way since I retired ,my father was the same.