From what I’m aware most people’s sleep patterns are based on a 24 hour period whereas they will sleep roughly 6-9 hours of that 24 hours around the same time everyday.
I assume this is a behavior evolved around earths 24 hour rotation period.
Are there any studies out there where someone was deprived of a clock and daylight (no way to tell what time of day it is) and what type of sleep patterns developed??
This thought came to me when wondering how one would adapt to life on another planet. Neptunes days are 18.4 hours for example. Would someone develop a sleep pattern based on an 18.4 hour day? Would they still sleep the same 6-9 hours or would it be shortened since their “awake” time would also be shortened?
In the long run would someone living on Neptune get more or less “awake” time over the course of 8760 hours (one earth year) than someone on earth who roughly gets 2/3 of their year in “awake” hours?
I think you are referring to circadian rhythms.
I remember seeing a documentary several years ago (probably Horizon/Nova) where a volunteer was isolated in an extremely deep cave. (Isolation from natural light, weather, air pressure changes, temperature etc.) and studied.
I think the outcome is that without external cues, the human body adopts a 25ish hour day.
How adaptable that would be to other planets is probably not known.
I expect NASA will have done some research on this too.
The study was Michael Siffre, a French spelunker; he spent two months in a cave in 1962, and six months in a cave in 1975. His sleep pattern varied wildly, sometimes spending 36 hours awake followed by 12-15 hours asleep. He reported being depressed for years afterwards. Another guy, Jurgen Aschoff, built a place he called “Tier Bunker” where he isolated subjects for 3-4 weeks; he reported they developed 25 hour sleep cycles. Other studies say it’s closer to 24.
In relation to this, I’ve often wondered about folks who live up north (Iceland? Greenland? Alaska?), where it’s daylight for so many months out of the year. Do they sleep in the p.m. or a.m.? I mean, I’m assuming humans evolved sleeping when it was dark because you couldn’t see well to hunt, gather, travel, etc, and were tired from doing all that during the day. So those that have sunlight all the time, what kind of schedule do their bodies adapt to?
I seem to remember that the bunker experiment showed that when people were encouraged not to defy sleepiness, they tended to nap in the late afternoon (although they weren’t to know the time of day precisely). Of course it’s difficult to see whether that was a function of isolation/boredom etc or a real preference of the body (well, mind really).
Hmmm… I’m more inclined to believe the “varied wildly” result. In the Tier Bunker and other studies, are they reporting an average sleep cycle? It’s hard for me to believe everyone in those studies locked into exactly 24 or 25 hour cycles. Any idea what the variance was?