I would be in Wolf and Moonstalker's camp here... (Moonstalker - what an appropriate name.) I used to say that my sleep schedule was all messed up, but I don't anymore. I embrace it, it works for me, it's flexible. I am self-employed, usually work evenings, and function very well evenings. One of my very favorite things to do (I consider it a luxury) is to fall asleep when I want to sleep and not set an alarm - I like to wake up and get up when I'm ready to do so. I don't usually oversleep unless I'm compensating for previous lack of sleep, just need the extra rest, or I'm depressed.
I do set my alarm if I have to get up in a few hours and want to make sure I don't oversleep.
I'm just a night owl. Even as a child. I didn't want to sleep at night. It doesn't matter if I'm awake all day and exhausted in the evening, I just don't want to sleep before 2 am. I'll fight it.
Several years ago, my holistic practitioner muscle tested that my body did not produce melatonin. So she recommended that I take some around 6 pm so I can fall asleep at night... uh, I'm not sure why/if I saw her for that issue because I never bought the melatonin. I thought about it, but my nocturnal instinct was probably like, "Ah, you don't really want it."
Very generally, my "natural" schedule is to go to bed around 4 am - give or take four hours. I often go to bed at 6 am or 8 am. I get plenty of afternoon sunlight and I darken pretty easily, so I'm not lacking any sun (not in so cal!). In addition, my sleep schedule changes if I have to or choose to be awake earlier in the day. And sometimes I'm like on a 36-hour or 48-hour "day" schedule. But like Wolf, I feel relieved to avoid the hot daytime sun of Southern California. I shut out most of the daylight in my bedroom while sleeping and it just feels right for me to rest during this time of day.
I'm sure in paleo times there was the small majority who were nocturnal. Even just for safety - nightwatches. And just because today we would feel so uncomfortable/vulnerable/bored if we were to mill about in the dark nighttime without the modern conveniences of electric light or fire, paleo people had to be like a different breed. Even AV talks about the night vision he developed from living outdoors (WWTL pg. 119). Imagine the night vision we - er, I mean, paleo people had living in real darkness every night (except for moon and stars). Just as we have night workers today (bartenders, graveyard shift workers, bouncers, police officers, etc.), I can totally see the paleo night hunters - hunting in darkness, even without moonlight - supplementing the group's diet with nocturnal prey. Paleo people were a different breed. Imagine how heightened their other-than-visual senses were. And being in tune with their environment, directly connected to their source of sustenance (the supreme locavore), and just vibing with the earth. I'm sure it was rough, but survival is its own meditation.
So I don't believe that people who stay up all night and sleep during the day are doing it all wrong, but it's definitely not for everyone. I've read that a daily routine - and a diurnal one - contributes to health, youthfulness, well-being, etc., but I've adapted to my nocturnality instead of fighting it, so I don't think it has aged or worn me out. Wolf, Moonstalker, and I were probably the ones looking out for our diurnal paleo buddies while they slept - so no nocturnal sasquatch or giant cat snatched you up. And we got you fresh nocturnal meat to enjoy upon waking.
Oh and lastly, I think paleo sleep cycles were likely very different. I can function well with two 4-hour nap sessions spread out in 24 hours. In other words, I doubt that the majority of diurnal paleos tucked in at 10:00 pm and slept soundly (even on such a great RPD
) for six hours or so. Depending on the climate and environment (dangers, predatory animals, etc.), paleos probably napped 3 hours here, nighthunted a couple hours there, slept in a cool cave for 5 hours during extreme daytime temperatures here, etc. Just as the RPD frequency of eating and the amount eaten in one or a couple (maybe a few) sittings are so widely variant and different from the "3 square meals" or "5 smaller meals per day" of today's modern eating, I'm sure paleo sleep/rest/catnap - frequency and amount - was way different from modern sleeping today. The end.