Do you often find yourself waking up at night four hours after falling asleep, then staying up for a couple hours and falling asleep for another four hours? If so, you are probably engaging in biphasic sleeping, which is “the most natural sleep pattern.”
I learned about biphasic sleeping from this article I read on Live Science.
It appears that we humans used to sleep in “two four-hour blocks, which were separated by a period of wakefulness in the middle of the night lasting an hour or more” according to Roger Ekirch. In fact, “a sleep scientist named Thomas Wehr discovered that everyone sleeps biphasically when subjected to natural patterns of light and dark.”
Ekirch explained that in the past, and especially during winter, darkness spanned up to 14 hours each night. Except for those affluent enough to burn candles for hours, folks were left with little to do but go to bed early, and this gave a great deal of flexibility to their nightly sleep requirements. Segmented or biphasic sleep patterns evolved to fill the long stretch of nighttime, and as observed by anthropologists, segmented sleep continues to be the norm for many people in undeveloped parts of the world, such as the Tiv group in Central Nigeria.
So why have did we start engaging in longer blocks of sleep? Well, you can thank Thomas Edison and the Industrial Revolution for that. Edison’s invention of the light bulb provided “articifial lighting” that “prolonged our experience of daylight, allowing us to be productive for longer” resulting in a shorter night for us, meaning we had to cram all our sleep into a short block.
Biphasic sleeping also “makes it easier to recall and access dreams.”
Maybe I will leave my lights off longer for this year’s Earth Hour so I can sleep in two four hour blocks. The question remains though. What am I going to do during those two hours I’m awake between midnight and two AM?