Polyphasic Sleep: The Natural Sleeping Schedule

Man SleepingWith all this information about sleeping and the myriad different sleeping schedules, you might wonder what the natural or normal sleeping schedule is. As it turns out, it isn’t as simple as “we are awake during the day, sleep at night” – not by a long shot.

Newborns practice a form of polyphasic sleeping. They are awake for short periods, and sleep for nearly two-thirds of the day. Most people will point to the “circadian rhythm” when talking about sleep schedules, indicating that the normal 24-hour period is “normal.”

Altering the circadian rhythm

As it turns out, the circadian rhythm is remarkably adaptable. Humans have been trained to both shorten and lengthen the time their bodies expect a day to last, according to this.  Studies have been performed to both shorten the circadian rhythm to 23.5 hours as well as lengthen rhythm to 24 hours, 40 minutes (incidentally, the length of a day on Mars). Studies have also been done which eliminate all external lighting cues for sleep and found that humans will slowly adapt a 25 hour “day” given no stimulus.

Sleep Schedules before the modern world

In the 1600s, it was widely considered normal to have a “first sleep” and “second sleep” with a 1 to 2 hour period of wakefulness between. People might wake, use the restroom, converse, and perform other activities, according to this article.  By the 1700s, this first/second sleep idea had mostly disappeared. The take away from all this is that humans are very adaptable, and that different sleep schedules are very possible. Over the course of human history, many different sleep schedules evolved naturally, and that how and when you sleep can be modified as you would like.

Photo: Chad Fitz

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