Should we embrace bi-phasic sleep?

Like a lot of people, I suffer from frequent bouts of insomnia. At least that’s what I thought it was. I can get to sleep easily enough but tend to wake up regularly in the early hours of the morning. I used to then lie there, trying to get back to sleep and worrying about not being able to. But more recently I decided to get up, make myself a cup of tea and read for a bit instead. Sometimes I might do a bit of work or a few chores and on a few occasions, I decided to make bread!

The author often finds herself waking up at night 

Giving in to wakefulness seemed to be the answer. After an hour or so, I would feel tired again and could return to bed—and to sleep. I’d wake in the morning, feeling far more refreshed than if I’d stayed in bed trying to sleep.  

Unwittingly, I have since discovered I had adopted a sleeping pattern that was the norm throughout history: sleeping in two shifts. Bi-phasic or bi-modal sleeping was considered the norm in the pre-industrial world and there are numerous written references to it. From Greek and Roman writers to Chaucer, Shakespeare and Dickens, in literature, diaries, letters, newspaper articles, plays and even court testimonies, there are accounts of people taking their first and second sleeps. 

While researching a chapter for his book A Day’s Close: Night in Times Past, historian A. Roger Ekirch began, from these references, to piece together a pattern of sleeping patterns that were very different to our contemporary notion of a good night’s sleep. Typically, our antecedents seemed to go to sleep as early as between 9pm and 11pm, and wake again between midnight and 2am for a couple of hours. During these hours they would perform a few household chores such as chopping wood, stoking the fire or sewing. Those who had livestock would tend to their animals, while inhabitants of religious orders used the time for prayer.

It was also apparently a great time for sex as couples were refreshed after their first sleep and could settle down for their second sated! The second sleep continued until the morning and this sleeping pattern was widespread across all continents throughout the preindustrial world.   

There is still evidence for it in the animal kingdom where many species have two or more separate spells of rest. An example is the ring-tailed lemur, which is neither nocturnal nor diurnal. These creatures go about their business both in the day and for a short spell during the night just as our forbears did.  

The ring-tailed lemur sleeps in shifts

Sleeping in shifts appears to have been the norm right up until the industrial revolution when factory shifts were long and the advent of artificial lighting allowed people to stay up later in the evenings. Because they still had to be up early for work, their sleep became compressed into one longer sleep broken only by the need to urinate. Almost overnight, a single seven or eight hour sleep become the new norm.  

But given long dark nights people seem to revert fairly quickly to patterns of split sleeping. In a study at America’s National Institute of Mental Health, adults were asked to be in bed in the dark for 14 hours. After a few nights, most of them segmented their sleep. Another put adolescents to bed in the dark for three 18-hour nights and, again, after a night or two, they began to sleep in in distinct chunks.   

Different sleeping patterns will suit different people

“Sleep duration has its limits,” explains Professor Mary Carskadon, director of the Sleep Research Lab on Rhode Island. “When given so much darkness, it made sense to have segmented sleep. And, where shift workers have challenges to their circadian timing system, which can cause various physical issues, I am unaware of any risks of this type of sleep segmentation. Some individuals find it restful; others find themselves increasingly productive at night. I'd say it's an individual thing.”   

For someone like myself, whose circadian rhythms appear to be stuck in the preindustrial era, this is good news. Unable to sleep through the night, it’s easy to think of yourself as an insomniac and further disrupt your sleep by fretting about not sleeping “properly.” 

In the modern world, we have been conditioned into believing that a single seven or eight hours solid sleep is what we need and remained largely in the dark about the historical practice of sleeping twice. 

For me, learning that for millennia two sleeps had been the norm took away the stigma of sleeplessness and allowed me to break my sleep for an hour or so during the night without worrying. I now make better use of my waking hours and can sleep soundly—twice.  

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