Sleep is better in two four-hour blocks?

I am one of those people who can fall asleep almost anywhere at almost any time, even on planes. But in addition to such naps, I also value getting a good continuous night’s rest, which is usually conceived of as about eight hours of uninterrupted sleep.

So I was surprised by this report of a study that said that that might not be optimum, that two segments of four hours separated by wakefulness of an hour or two may be more natural. Apparently, records of lifestyles before the modern era suggested that this was common practice.

During this waking period people were quite active. They often got up, went to the toilet or smoked tobacco and some even visited neighbours. Most people stayed in bed, read, wrote and often prayed. Countless prayer manuals from the late 15th Century offered special prayers for the hours in between sleeps.

And these hours weren’t entirely solitary – people often chatted to bed-fellows or had sex.

A doctor’s manual from 16th Century France even advised couples that the best time to conceive was not at the end of a long day’s labour but “after the first sleep”, when “they have more enjoyment” and “do it better”.

Since there is an average of 11 hours of darkness, this pattern pretty much covers that period, which might have been convenient when there was no electricity.

The practice apparently started to fade by the dawn of the 18th century.


  1. Henry Gale says

    One of the things I wonder about is why evolution hasn’t reduced sleep to nothing or at least micro-naps.

    We know people exist who require very little sleep and it would seem that sleeping is an activity that puts one in danger.

    I just wonder why the trait for requiring less sleep isn’t far more common.

  2. starskeptic says

    You made my day; after years of working 3rd shift -- 2 periods of 4 hrs of sleep is normal for me. I thought I was missing out on something important…

  3. starskeptic says

    I saw a lecture by Francis Crick at N.I.U. in the late 1980’s about A.I., neural-nets and consciousness. His studies suggested that a lot of information restructuring goes on during sleep.
    “…sleeping is an activity that puts one in danger.” -- in our evolutionary past -- it was walking around after dark that put us in more danger…

  4. says

    Some twenty years of sailing small boats across oceans using various watch-keeping schemes, that varied from three hrs on -- six hrs off to the four on -- four plan off seems to provide support for this study, in an anecdotal way. The different watch plans are dependent upon the number in the boat’s crew.

    There are now folks who teach single-handing sailors the best methods for maintaining alertness while at the same time getting enough rest to keep sailing in a relatively safe manner. Things can go wrong out there in the deep blue and being able to cope with problems safely, demands that the sailor be rested when the situation calls for it. Sleeping for long periods while sailing may actually result in sticky situations.

    So where did the idea of eight hours continuous sleep being a necessity originate?

  5. says

    I can’t imagine my body being capable of waking up in the middle of the night. I wonder if it would be more detrimental than a straight 8 hour sleep to set an alarm for 4 hours and force yourself to do something for an hour before going to sleep again!

  6. oldebabe says

    Requirements of sleep are just like personal characteristics, ISTM, and seem to change over time, i.e. my sleep needs have changed since I became aged. Some require a lot of sleep, some nap a lot, some sleep seldom, some wake often, some people can’t get to sleep easily, etc etc. etc. Whatever brain and body needs are satisfied through sleep, are, apparently, satisfied in different ways and in different amounts for different folks.

    I don’t know what’s the healthiest, and I don’t think one should force oneself to do what
    someone else says that that is what is needed, if it doesn’t line up with the reality. So, as always, I think the best bet is to listen to what your body tells you is needed, and accommodate. If you’re wakeful, get up. If you’re sleepy, get some sleep. Not exactly rocket science…

  7. says

    Ok, this is just a sample point of ONE and therefore means little:

    usually I sleep in one long block (7 hours is typical). But on occasion I attempt very long walking races (24 hours, or 100 miles (161 km)). In the week (or two) following one of these long races, I CANNOT sleep straight. I sleep 3-4 hours, wake up…putz around, then go to sleep for another 3-4 hours. Eventually, my patterns return to normal.

    My point: when I am the most physically tired, I tend to sleep in those small chunks.

  8. P Smith says

    I worked my way through college as a security guard, working evenings and weekends, because it didn’t interfere with my classes and I could do some studying on the job. It meant years of polyphasic sleep, working nights and studying days, and fitting sleep in between.

    I may have graduated with little student loan debt, but I ended up with more than 20 years of abnormal waking and sleeping patterns -- shifting waking periods, occasionally having long periods of wakefulness (up to 40 hours) or sleep (up to 20) and other oddities. It has never impaired my ability to work or function so doctors wouldn’t treat it, but I’d rather not have it.


  9. P Smith says

    You should read up on Leonardo Da Vinci’s alleged/reported sleep schedule, where he claimed to sleep less than four hours per day, as well as other claimed methods of sleeping.

    Others have made claims of the ability to get by on less sleep using frequent naps, but I have no opinion on whether it works. It’s fine for cats, but is it okay for humans or primates? The thing I hate about polyphasic sleeping is frequent yawning and drowsiness, not good things to have when working, especially when driving.

  10. says

    Shalom Mano,

    I read the same BBC article and found it intriguing because it informed me about what I have also assumed to be my atypical sleep patterns. Since reading the piece I’ve begun experimenting with allowing my natural patterns to emerge and I’m enjoying what I’m finding.



  11. God's creation says

    just sleep according to what your body needs it. Dont need to listen to what others say or what is written. it is not about characteristic or what. Just listen to your body. Eat well to and you will sleep well.

  12. says

    Perhaps due to Lyme bacteria messing with my brain, the last two nights my normal 7 hour solid pattern has switched to a 3-4 hour pattern. I just wake spontaneously after about 4 hours now. Am I getting Delta wave sleep, the deepest which happens at the end of the sleep cycle? If this keeps up I’ll get a sleep study done.


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