I wonder where the cutoff is, when we get older. My older neighbors and others like my grandfather would stay up until 2 or 3 in the morning and then get up at like 8 am, barely sleeping 5 or 6 hours. I wouldn't be able to maintain that long term that's for sure!

Yeah, I think it also happens occasionally for my mom here, going to bed by 3am yet waking up at around 7am. But it gets really hard to function during the day without getting a nap sometime within the day. I think the system can't cope much with less sleep and substitutes like coffee can only take us so far!