The truth about 'split sleeping' – and what to do if you wake in the middle of the night

You wake with a start. The world around you is pitch black. Your partner is sleeping, provocatively peacefully. You reach for the alarm clock, then curse it. It’s 3am. Again. Why does this keep happening? Is it symptomatic of stress; a sign of something even more sinister? Or perhaps we’re worrying needlessly, manufacturing a “health crisis”?

“This was the whole reason I wrote my book,” says Russell Foster, professor of circadian neuroscience at Oxford University and author of Life Time: The New Science of the Body Clock. “I wanted to say: here’s the science. Now stop worrying about it.”

In many ways, the human race has never been better set up for sleep. Soft beds, anti-allergy bedding, weighted and electric blankets abound. And yet, believes Foster, “we’ve become so worried about our sleep – there’s now a real condition called sleep anxiety.” 

Apps, products and – yes – newspapers tell us we must have eight, pure and uninterrupted hours of sleep, or else suffer dire consequences. However, says Foster: “Waking up in the middle of the night is, broadly speaking, the natural form of sleep. When people accept that, they get the best sleep they ever had.”

The historian A. Roger Ekirch is largely responsible for this discovery. In the 1990s, while researching the history of nighttime, he began encountering a mysterious phrase: “first sleep”. The Greek philosopher Plutarch mentions it. Cervantes writes of Don Quixote: “Being satisfied with his first sleep, did not solicit more.” 

“Its prevalence as the predominant pattern of Western slumber stretched from antiquity to the mid-19th century,” says Ekirch. Until electric lighting and strict factory schedules interfered, it was common to sleep in two shifts: slumbering till somewhere around midnight, then waking naturally for a couple of hours.

This “interval of wakefulness” was so routine, it was common for people to complete “mundane activities such as prayer, study, and unskilled chores that required minimal light,” explains Ekirch. Though others had more fun, he admits. 

Around the same time as Ekirch was making his discoveries, the psychiatrist Thomas Wehr was conducting experiments in which he deprived test subjects of light, and other distractions, for 14 hours out of every 24. After a month, their sleep patterns evolved from a single long stretch to two, separated by a wakeful period of between one and three hours.

“Studies going on now in South American cultures, where there’s no electric light, are finding similar fragmented patterns,” says Foster. “So I think we’ve got enough evidence that our natural pattern is not this mythical eight hours of consolidated sleep. It is much more likely to be polyphasic or biphasic,” which is sleeping in two or multiple phases, instead of a single block. We do not know yet what health benefits biphasic sleep might have over the conventional model, but that hasn’t stopped split-sleeping becoming the latest productivity hack.

“Too many people who have split sleep patterns have the ill-judged belief that it will optimise their performance,” says James Wilson, a sleep expert (also known as The Sleep Geek) who has founded an organisation called Kip Mate that helps organisations, sports teams and individuals get better sleep. “In my experience, working with tens of thousands of poor sleepers every year, it generally doesn’t.”

But what of all the poets and rock stars who wake naturally at 2am with an entire poem or song fully formed in their minds? The myth of middle-of-the-night creativity may not be totally unfounded. “It could be that you’ve experienced the first period of sleep, when you’re having most of your slow wave sleep, and it’s likely that’s where information processing and memory consolidation is taking place,” says Foster. “You may have woken up with that partial idea, and then you can work on it.” 

If the muses naturally wake you at 2am, and you can sleep in later to compensate, then run with it, he suggests. Others, however, will find themselves waking for more prosaic reasons. “The amplitude of our circadian rhythms drops as we age,” explains Foster. “It has a number of consequences. The circadian drive for sleep and wake is not so pronounced.” The hormonal regulation of our urine production – which would usually tell our bodies to produce lots in the day, and little at night – weakens too. So you may wake up needing a wee.

Nocturnal bathroom trips can be minimised by moving around more before bed (among those of a certain age with sedentary habits, he explains, as much as a litre of urine can be generated when you lie down to sleep, as a result of reintegrating that fluid that’s accumulated in your ankles and feet). Also, “get outside early,” says Foster, “as morning light in particular is very good at setting the clock and therefore the sleep-wake timing.”

If you do wake up after your “first sleep”, keep the lights low, perhaps play some soporific music. Don’t check the news or emails, but picking up a Kindle is fine. “If the sight of the early hour alarms you, cover the dial on your clock,” counsels Foster. “What you need to do is enhance your ability to fall back to sleep.”

But most of all, he pleads: “I wouldn’t worry about waking up.”