There have been a lot of articles on this topic in the last year or two. Here's another recent article, this one from The Guardian: Sleep: why they used to do it twice a night.
I find this information very useful, because it helps me relax when I do wake for a spell in the middle of the night. I'm trying to go to bed early (9 pm or so), to sleep in a very dark room, and to let my body decide whether to wake in the night or not. I often wake in the night now, but no big deal.
I feel incredibly well-rested these days!
I agree with AnnaA that natural patterns are very inconvenient/impractical when you have an intense daily schedule and must rise at a fixed time.
Natural sleep patterns work beautifully when you have the luxury of going to bed very early (first feeling of drowsiness 2-3 hours after dusk) and can calmly enjoy meditative thought when you wake at about midnight - 1 am and then sleep until the sun is up (currently about 6:30 am where I live.)
What I described above is my sleep pattern now that I am well nourished and don't work. It would have been totally impossible--and never happened--when I was working. The approach I had to follow then was to stay up late enough that I would either sleep straight through or wake up but go right back to sleep.
I guess it boils down to the fact that we shouldn't get upset if we have broken sleep. We all seem to do it at some time or the other and getting upset over it just makes it worse in my opinion.
It is, however, NOT convenient when the second phase of sleep is disrupted by an alarm clock because you need to get up for work. This happened to me quite frequently during menopause and it was a royal pain in the butt, making me even crankier than normal!
Over 30% of the medical conditions physicians treat are related to sleep deprivation... that's absolutely incredible. It makes sense, however, as sleep is intricately tied to overall health (hormonal levels, mental capacity, etc.) Thanks for sharing this study. How exactly did you come across it? Do you read that blog regularly?
They are studying Neolithic habits from sources that never heard of the pineal gland.
Your body is best adapted to sleep at dark and wake up at night, unless you live above the Arctic circle. :)
Yeah, I saw this article and loved it. I usually wake up at about 2 or 3 in the morning, and my legs are twitchy and if I stay in bed it wakes up my DH. So I go downstairs, do some yoga stretches, drink a glass of water, and then go back to bed. Invariably I go right back to sleep. The article reassured me that my waking pattern was normal and that it wasn't necessary to have 8 hours of uninterrupted sleep to be well rested the next day.
I thought the article was fascinating, especially how they dug up literature for their theory. It has caused me to rethink the times I wake up during the night. When I am tired with not much going on in the evening, sometimes I do fall asleep early and then wake up around 1. Maybe that is not such a bad thing?