Did you know that your ancestors generally slept twice in a single night? Research has shown that it’s true; people in the 1700s and earlier usually got two sleep periods in per night – one from early in the evening, shortly after sunset, that lasted about five hours, and then another from from around three or four AM to first light. The modern “eight hours a night” that is supposed to occur all in one shot didn’t come into general use until around 1800 or so.
So why did humanity change? No one knows for sure, but most people who have studied the phenomenon argue that it has to do with extending our daylight hours with the use of artificial light. Electric lights didn’t come into widespread use until around the twentieth century, of course, but gas lighting from various sources was used extensively starting in the 1790s. In the early 1800s people began to set up gas lighting in their own homes, the first gas lighting companies were formed, and by 1820 European cities like Paris were adopting gas lighting for their streets. In America, Baltimore was the first to use it.
Today, both gas lighting and “two-sleeps” have disappeared so far into the past that most young people don’t even know that they existed. But some experiments (both scientific and anecdotal) have shown that humans who follow what might be termed “natural light lifestyles” usually fall back into the two-sleep pattern. And this raises the question: are two sleeps better than one, especially for those who have trouble sleeping in the first place?
The jury is still very much out on this one, but a few common sense observations can be made:
1. More overall rest
If you’re sleeping in two large blocks vs one huge one, chances are good that you’re going to get more overall rest. The reason? Even if your total sleep time is the same, the in-between waking period is almost certainly going to be less harried and frenetic than the same amount of time if it were experienced one on side or the other of sleep…i.e., during daylight or early evening hours.
Also, some sources say that you actually need less overall sleep time if you break it up into pieces. In fact, there may be an inverse correlation between frequency of sleep and overall sleep time. The most extreme example I know of is put forth in Tim Ferriss’s The 4-Hour Body, which goes so far as to cite cases where regular 20-minute naps spaced four hours apart throughout the 24-hour day–a total of two hours’ sleep–provide just as much rest as one eight-hour period. (If you buy this book, I heartily recommend getting the hardback edition, as the Kindle version just doesn’t display the various charts and so on very well.)
2. A lá the above point, you can use the in-between awake period to do something quiet like read or meditate, so it might have a beneficial effect on certain people whose lives are more harried than average. Or people who simply have a harder time coping and need more down-time.
Even if you use the period to work, chances are that you’ll be able to focus better. You’ll get your stuff done quietly, efficiently, and without a lot of distractions. After all, not too many of your friends are going to call at 3:30 in the morning. Just make sure you have your internet turned off.
3. No anxiety about waking up in the middle of the night. For insomniacs, this is probably the most important point of all. If you’re planning on two sleeps when you turn in (for the first time), waking up will be the most natural thing in the world, not a cause for that all-too-familiar, wee-hours-of-the-morning dread. You won’t sweat it at all, and so will be less likely to let your own mind get the better of you. In fact, it might actually be a comfort to know that your distant ancestors did exactly the same thing every single night of their lives.