I always needed more than 8 hrs of sleep, now that I am into my 50s, I feel well after 4 hours. Anecdotes are good. My grandfather got to 100 not sleeping more than a few hours a night after he turned 55 and he raised my cousins as their parents were shite. I know whining young parents who complain about lack of sleep, I know older parents who never do as they were happy finally having a kid. Etc.