How much sleep anyone needs is dependent on how quickly their brain can descend into REM sleep, which is the sleep the brain and body actually need.
In a typical ten hours sleep cycle, the brain may spend three hours descending into REM, four hours there, and then three hours re-emerging again. So in fact, the brain only needs the four hours of that sleep cycle.
Those whose brains grow straight into REM need only a few hours a night - Margaret Thatcher was famously one of them.
I am unsure if she is a typical example, but if she is, her acknowledged lack of humour and tendency to want total control means that if that's what it takes, I will stay as I am.
I am sixty, and if left, I can sleep from say, eleven at night, through till three the next afternoon, and still sleep through the next night and wake around eleven in the morning, if left again.
I have always had these sleep patterns - I think I was a sloth in a former life!