Sorry, You Probably Can't Sleep Just 6 Hours A Night

Reading between the lines of a recent study on the sleep habits of indigenous people.
The Hadza people, or Hadzabe'e, are an ethnic group in north-central Tanzania, living around Lake Eyasi in the central Rift Valley and in the neighboring Serengeti Plateau.
Kerstin Geier via Getty Images
The Hadza people, or Hadzabe'e, are an ethnic group in north-central Tanzania, living around Lake Eyasi in the central Rift Valley and in the neighboring Serengeti Plateau.

A recent study published in Current Biology on the sleep habits of three "pre-industrial" societies has been making waves in science journalism circles for suggesting that we don't need to sleep eight hours a night. The study found that the hunter-gatherers in question, who live in South America and Africa, sleep between 5.7 and 7.1 hours a night on average, which the authors suggest is no more than "modern" humans. The research has touched off a wave of reports that public health recommendations to sleep 7-8 hours a night are overblown.

Both the study and its coverage bear a second look.

Reading between the lines

Exaggerating the takeaways of an isolated finding is nothing new; science reporting turns on the revelation of headline-sized takeaways from dense research. In writing up the sleep study, news outlets honed in on the ostensible guilt of those who don't get eight hours of shuteye.

"Not Getting 8 Hours of Sleep? Neither Do Hunter-Gatherers," Newsweek reassures readers. The New York Times suggests that the study's findings counter "health authorities [who] have long suggested that poor sleep is rampant in America," and strikes a populist note by quoting a sleep expert who says, “It’s difficult to envision how we can claim that Western society is highly sleep deprived if these groups... sleep less or about the same amount as the average Joe does here in North America."

And on New York magazine's blog "The Science of Us," a report on the study begins, "You would get so much more sleep if not for the modern evils of electricity, TV, and the internet, right?" This type of coverage seeks to extrapolate the findings of a single study to assuage some collective guilt about not sleeping enough that we receive from a shrewish public health agenda.

Few reports seem to consider the finer points of study in full, all 22 pages of which are available online. For instance, all the three hunter-gatherer societies were found to have a "sleep period," or the time they were actually in bed, of roughly seven to eight and a half hours -- exactly what is generally recommended for the public.

The "Paleo Effect"

The study may also be garnering press inches because it capitalizes on the current vogue for "pre-industrial" modes of living. Between the super-popular paleo diet and "evolutionary fitness" that involves pushing heavy things around, never have Americans been so invested in ancestral ways of life. The language of a premodern Eden is omnipresent in the study, from its title "Natural Sleep and Its Seasonal Variations in Three Pre-industrial Societies" to the founding question of its abstract, "How did humans sleep before the modern era?"

So while the research methods may be sound, the spirit of its inquiry seems like a leading question. The hunter-gatherers under study acquire the luster of being accidental upholders of a purer, ancient way of life that is implicitly superior to our own. This likely contributes to its reception within a reading public that has certain pre-formed ideas about such societies.

Moreover, just how useful is it to compare life in a hunter-gatherer society to life in modern-day America as a way to determine how much sleep human beings actually need? We face dissimilar and "perhaps more nagging stressors" than our ancestors did, University of Pennsylvania sleep researcher David Dinges told Newsweek. The effect of electronics on sleep quality can't be overstated, and is well-documented in a battery of research.

In fact, a 2012-13 study demonstrated the sleep-disrupting effects of electronics even between two groups of indigenous hunter-gatherers in South America!

This study's findings are doubtless valuable. But in terms of applications for our own lives, it's not very productive to think of electronics as some modern evil that foil our every effort to get shuteye. We're better served by practical suggestions that account for our electronics, like going offline an hour before bedtime or installing blackout curtains in the bedroom.

Public and Private Health

If anything, sleep deprivation remains underrated as a threat to public health. Drowsy driving causes 100,000 accidents a year, according to the National Highway Traffic Safety Administration. People who don't sleep enough are more likely to suffer from chronic diseases such as hypertension, diabetes, depression, and obesity, and even from cancer, according to the CDC. Sleep deprivation has been linked to a number of infamous accidents, from the Challenger explosion to the Exxon Valdez spill.

Lack of sleep costs more than $2500 per person per year in lost workplace productivity, and insomniacs miss on average 5 days more of work than their peers who get the sleep they need.

So the problem with posing one study as a counterpoint to the whole notion of getting 7-8 hours of sleep every night is not only sensationalism, but irresponsibility. Science shouldn't be approached from an intent to justify a lifestyle.

The Upshot
Still, the study is not without its merits. It frames sleep as a profoundly natural activity, rather than something to be medicated or pathologized. That underscores the real risk of sleep scare tactics, which is the over-prescription and abuse of sleep aids.

It also suggests, helpfully, that sleep is a highly personal endeavor, so you really should sleep however much allows you to feel refreshed, and not some arbitrary number of hours. For most people, of course, this remains 7-8 hours. But that figure shouldn't be taken as a public health admonishment, so much as a personal metric to which most of us are naturally attuned.

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