Has the 8-hour sleep cycle outlived its usefulness?

Sometime in the dark stretch of the night it happens. Perhaps it’s the chime of an incoming text message. Or your iPhone screen lights up to alert you to a new email.

Or you find yourself staring at the ceiling, replaying the day in your head. Next thing you know, you’re out of bed and engaged with the world, once again ignoring the often quoted fact that eight straight hours of sleep is essential.

Sound familiar? You’re not alone. Thanks in part to technology and its constant pinging and chiming, roughly 41 million people in the United States – nearly a third of all working adults – get six hours or fewer of sleep a night, according to a recent report from the Centres for Disease Control and Prevention.

And sleep deprivation is an affliction that crosses economic lines. About 42 per cent of workers in the mining industry are sleep-deprived, while about 27 per cent of financial or insurance industry workers share the same complaint.

Typically, mention of our ever increasing sleeplessness is followed by calls for earlier bedtimes and a longer night’s sleep. But this directive may be part of the problem.

Rather than helping us to get more rest, the tyranny of the eight-hour block reinforces a narrow conception of sleep and how we should approach it. Some of the time we spend tossing and turning may even result from misconceptions about sleep and our bodily needs: In fact neither our bodies nor our brains are built for the roughly one-third of our lives that we spend in bed.

The idea that we should sleep in eight-hour chunks is relatively recent. The world’s population sleeps in various and surprising ways. Millions of Chinese workers continue to put their heads on their desks for a nap of an hour or so after lunch, for example, and daytime napping is common from India to Spain.

One of the first signs that the emphasis on a straight eight-hour sleep had outlived its usefulness arose in the early 1990s, thanks to a history professor at Virginia Tech named A Roger Ekirch, who spent hours investigating the history of the night and began to notice strange references to sleep.

A character in the ‘Canterbury Tales,’ for instance, decides to go back to bed after her “first sleep.” A doctor in England wrote that the time between the ‘first sleep’ and the ‘second sleep’ was the best time for study and reflection. And one 16th-century French physician concluded that labourers were able to conceive more children because they waited until after their ‘first sleep’ to make love.

Historical existence

Ekirch soon learned that he wasn’t the only one who was on to the historical existence of alternate sleep cycles. In a fluke of history, Thomas A Wehr, a psychiatrist then working at the National Institute of Mental Health in Bethesda, Md., was conducting an experiment in which subjects were deprived of artificial light.

Without the illumination and distraction from light bulbs, televisions or computers, the subjects slept through the night, at least at first. But, after a while, Wehr noticed that subjects began to wake up a little after midnight, lie awake for a couple of hours and then drift back to sleep again, in the same pattern of segmented sleep that Ekirch saw referenced in historical records and early works of literature.

It seemed that, given a chance to be free of modern life, the body would naturally settle into a split sleep schedule. Subjects grew to like experiencing nighttime in a new way.

Once they broke their conception of what form sleep should come in, they looked forward to the time in the middle of the night as a chance for deep thinking of all kinds, whether in the form of self-reflection, getting a jump on the next day or amorous activity. Most of us, however, do not treat middle-of-the-night awakenings as a sign of a normal, functioning brain.

Doctors who peddle sleep aid products and call for more sleep may unintentionally reinforce the idea that there is something wrong or off-kilter about interrupted sleep cycles.

Sleep anxiety is a common result: We know we should be getting a good night’s rest but imagine we are doing something wrong if we awaken in the middle of the night. Related worries turn many of us into insomniacs and incite many to reach for sleeping pills or sleep aids, which reinforces a cycle that the Harvard psychologist Daniel M Wegner has called “the ironic processes of mental control.”

As we lie in our beds thinking about the sleep we’re not getting, we diminish the chances of enjoying a peaceful night’s rest. This, despite the fact that a number of recent studies suggest that any deep sleep – whether in an eight-hour block or a 30-minute nap – primes our brains to function at a higher level, letting us come up with better ideas, find solutions to puzzles more quickly, identify patterns faster and recall information more accurately.

In a Nasa-financed study, for example, a team of researchers led by David F Dinges, a professor at the University of Pennsylvania, found that letting subjects nap for as little as 24 minutes improved their cognitive performance.