What is 2-Part Sleep?
During “National Sleep Awareness Week,” which began as the National Sleep Foundation’s yearly campaign to remind people just how important it is to get a good night’s sleep, The Huffington Post and The Forum at Harvard School of Public Health worked together to create a live webcast event: “Fighting the Clock: How America’s Sleep Deficit is Damaging Long Term Health.”
In this clip Charles Czeisler, M.D., Ph.D., who is currently chief of the division of sleep medicine at Harvard Medical School, discusses historical sleep patterns. A “couple of hundred years ago,” he says, many people didn’t assume that they’d go to bed and sleep for a solid 8-hour period.
Instead, there are records that people expected two periods of sleep or “split sleep” during the night, and that many also took an afternoon nap or “siesta” as well. The nighttime was split into the “first sleep” or “dead sleep” and a “sweet sleep” in the early morning hours after a period of wakefulness.
The “dead sleep” was a deep sleep that usually began right after dusk, to shake off the exhaustion of physical daytime labor. In the middle of the night, people would expect to wake up — they might socialize, go to visit one another, or do a little recreational procreation with the energy from that first sleep. As the night wore on, folks would fall into the “sweet sleep,” a period of lighter sleep and dreaming before rising around sunrise.
According to Czeisler, sleep was “more divided” than today’s assumed 8-hour period. “The current idea that you have to go to the doctor and get a pill if you wake up in the middle of the night,” he says, “is probably misguided.”
Do you wake up in the middle of the night? Does it affect your alertness during the day?