This pattern of sleep is called 'bimodal' or segmented sleep - this way of sleeping has been documented as the 'normal' sleep pattern of pre-industrialized societies, i.e. before electric lighting was invented. Typically, the body reverts to it after a week or so of going to bed when it gets dark and sleeping in pitch black all night (except for the three nights around the full moon).

Although it has not been documented, a paleo/primal diet may also help move the body back into a segmented sleeping pattern and you may find that this is what your body is trying to do, although, 4.30 a.m. sounds as if it is not quite there yet.

Bimodal sleep is composed of two periods of sleep during the night, with a wakeful (or half wakeful) hour or two in the middle. In medieval England, the first (or dead) sleep and the second (or morning) sleep was well-known and the wakefulness in between (named dorveille – meaning ‘twixt sleep and wake – in French) was highly valued for its meditative and semi-dreamstate qualities. This was the time of quiet conversation, love-making or dream interpretation and soothsaying; a period of deep contemplation that we, with our electric lighting and 24-hour lives have all but lost.

Until the modern era, up to an hour or more of quiet wakefulness midway through the night interrupted the rest of most Western Europeans, not just napping shepherds and slumbering woodsmen. Families rose from their beds to urinate, smoke tobacco, and even visit close neighbors. Remaining abed, many persons also made love, prayed, and, most important, reflected on the dreams that typically preceded waking from their “first sleep.” Not only were these visions unusually vivid, but their images would have intruded far less on conscious thought had sleepers not stirred until dawn...... ......In addition to suggesting that consolidated sleep, such as we today experience, is unnatural, segmented slumber afforded the unconscious an expanded avenue to the waking world that has remained closed for most of the Industrial Age.

`Sleep We Have Lost’ by A. Roger Ekirch

So, to answer your question, you maybe feeling that you are not sleeping so well, but you should not feel any worse the wear for it, your body is probably trying to get back into its natural rhythm of two 'sleeps' per night, but - if you are still using electric lighting in the evening - cannot quite manage it. I would suggest using candlelight after dark, if it is at all possible, F.lux on your computer or just go to bed and wake earlier....(there is another paleohacks post about this subject) in fact, you will find that this maybe a chance to use a couple of hours during the night for meditation or something similar ;)

Here is another fascinating account of hunter/gatherer sleeping habits; studies on segmented sleep are cited in the last section (with this quotation from psychiatrist Thomas A. Wehr of the National Institute of Mental Health (NIMH) in Bethesda, Md. who conducted the studies in 1993: "A natural human sleep pattern may reassert itself in an unwelcome world and get labeled as a disorder").

I understand what you mean. I read Lights Out: Sleep, Sugar, and Survival and it lead me to going to bed within an hour of sundown.

After several weeks, I began to wake during the night, but always fell back to sleep rather easily after some time passed. Now I routinely wake up at sunrise.

I believe the answer by Louisa to be true. I get a net sleep of around 9 to 10 hours, awake in the night maybe an hour or two, but feel great during the day. I begin to get tired after sundown if I cut the electricity after dark.

Interesting. My sleep has massively improved on Paleo. It was, I think, cutting out the wheat/gluten that did it for me. Pre-paleo I used to have racing thoughts and could not fall asleep until 4am -- now I can actually lay down fall asleep around 10pm and wake up at 7am.

I have always slept very good, before and after going paleo. But a few months ago my sleep pattern changed (subjectively it felt worse) and I generally felt a bit less (that's a bit less that superb though).

After thinking for a while I thought it could be to the cod-liver oil I recently started taking, and maybe a bit too much, especially because I probably already had a good Vit A intake (butter). I stopped taking the CLO, and my sleep returned.

As always, with these little selfexperiments, it is dangerous to be fooled by randomness, or be fooled by other factors that are unknown...

I used to be a very sound sleeper and now I wake up a lot during the night....its a very restless sleep. However, I wake up easier (without an alarm) and don't feel tired at all. I fall asleep around 10-10:30 and usually sleep soundly for 2-3 hours. I then toss and turn a lot until I wake up around 6:30. Again, I actually feel much more awake though.

My sleep has also improved since I went Paleo. I have no trouble getting to sleep now, and I am bouncing awake instead of dragging myself out of bed.

Since years paleo my sleep depends totally on sunlight. Means in winter more and summer less time in bed. Also sleep deepness is less in summer. Which means often tired around 10pm, wake ups at 2am and absolutely wide awaken by 4am. Heavy disturbances with full moon. As long one awakes refreshed I would not worry about. It´s just primeval.

Not eating wheat makes my acid reflux better, thereby aiding sleep. I sleep well if I keep all light out of my eyes by using a sleep mask.

I wake up with two puppies pounding on the bed just now, so have no idea how long I would last without that wakeup call!

I find my sleep rhythm is different in winter and summer- summer I sleep less and in winter weather (especially heavy rain) I sleep more.

I've found that from losing much weight (I'm right around the 30 lb. mark) since starting Paleo and exercising, my snoring has dropped off to being non-existant. So not only do I sleep better, so does my wife. :)

I have recently found that I sleep very soundly all night if I have a hot sit down bath about 9pm, and then crawl into bed. No more bimodal sleep for me.

The other thing that has helped trememdously is supplementation with a small amount of plant sterols to control an enlarged prostate gland. This product http://www.vitacost.com/Source-Naturals-Beta-Sitosterol-Mega-Strength

Just a half a caplet twice a week prevents wake up to urinate for me.

This has been my experience too. I sleep deeply for a few hours and wake up in the mid-morning always. Thenceforth, I have light sleep replete with non-REM dreams (they feel more like day dreams and are not like living an experience, which is how REM dreams feel for me). Very interested in the bimodal sleep idea presented above...

I am fine with my reduced sleep since I feel more rested than I did before, even though I estimate I am getting only 3-4 hours of deep sleep and 2-3 hours of light sleep per night, with an average of about 6 total hours of sleep per night. I sleep in pitch blackness and give myself about 8-9 hours to rest, though, as stated, I cant seem to use it all.

I needed less sleep after switching to paleo. Perhaps you do, too-- if you only need 6 hours, laying down for 8 will make it seem like you're not sleeping well.

Insomnia is the main reason why I decided to quit the Paleo/Primal Diet after 3 months. There were many other reasons, but after a 2 week run of insomnia recently, I decided to add starches, grains, and legumes back to my diet. I've been sleeping like a baby ever since and feeling more energetic. By the way, I'm 5 feet 6 inches and 125 pounds. I am not out of shape nor am I unhealthy, but I was starting to get that way on the Paleo Diet. Restrictive diets/fad diets never live up to their hype. Oops, sorry guys, Paleo/Primal isn't a diet, it's a lifestyle, right?

My sleep is poor and hasn't improved, but 100 other things have, so I'm happy... I'd love to find the source of my bad sleep

User this is an old post but I'm wondering if anyone is still having sleep problems. I am 2 months in to my paleo eating and waking early (3-4, occasionally even 1-2) has been happening almost every night. Sometimes I can't go back to sleep for several hours and once in a while not at all! Unfortunately, I suffer through the day for it. I feel tired! Anyone else with this trouble?