People with insomnia typically worry about not getting enough sleep. It’s easy to understand why. The media are full of stories warning of the perils of insufficient sleep: obesity, diabetes, dementia, cardiovascular disease.
The Centers for Disease Control and Prevention for several years declared insufficient sleep to be a public health epidemic (last year they revised the language to “public health problem”). And according to an estimate set forth in Sleepless in America, a documentary released on the National Geographic Channel in December 2014, Americans sleep considerably less than we did 150 years ago.
But a study of sleep in 3 traditional societies published in October suggests that humans may need less sleep than we think we do—which should give insomniacs food for thought.
Making Inferences About Sleep in Times Past
How did people sleep millennia ago? Has electric lighting really had as negative an impact on sleep as sleep experts claim it has?
The scientists and anthropologists who conducted this study couldn’t travel back in time to assess the sleep of our ancestors. So they did the next best thing: study the sleep of 3 hunter–gatherer and hunter–horticultural societies in existence today. These traditional peoples, who live without electricity or any modern technology, live in equatorial regions of Tanzania, Namibia, and Bolivia.
What They Found Out
The investigators used wristwatch-type devices to measure sleep duration and light exposure for 94 adults over a total of 1,165 days. Following are some interesting findings:
- People in these traditional cultures slept 5.7 to 7.1 hours a night—less than average sleepers in modern industrialized societies like the United States. Yet extensive research has found that although their daily energy expenditure is about equal to that of most Americans, they’re healthier and more physically fit than we are.
- People did not go to sleep at sunset, as has been assumed about people before the advent of artificial lighting. On average, they went to sleep 3.3 hours after sunset, keeping vigil in the dark except for a small fire and moonlight. So electric lighting is probably not the only reason we like to stay up to watch the late show. Perhaps Thomas Edison did not have as big an impact on sleep as we think.
- People got their sleep in a single sleep episode uninterrupted by long periods of wakefulness. Daytime naps were the exception rather than the rule. This challenges the idea that early humans had two separate sleep episodes interrupted by a wakeful period in the middle of the night, or that they routinely took daytime siestas.
Relevance to Insomnia
Many people with insomnia say they need 8 hours of sleep a night, and maybe some of us do. Yet although this study by itself is not evidence that we need any less, if it convinced us to revise our beliefs about sleep need downwards, it wouldn’t be a bad thing.
Sleep therapists say that one thing that happens to many insomniacs as their sleep improves is that they let go of the idea that 8 is the magic number. Sleep quality may matter more than the number of hours we get.
Why Such Alarmist Messages?
Sleep isn’t always seen as important—yet it is a pillar of health alongside diet and exercise. But the alarmist tone of some of the messages we hear about not getting enough sleep (“a public health epidemic”), and the fact that healthy sleep is almost always defined as a certain number of hours, is worrisome to people with insomnia and others whose nightly share of shut-eye falls short. How helpful are such messages really?
The cynic in me says the pharmaceutical companies and medical device makers are behind this campaign to insist that we aren’t getting the sleep we need. Because who stands to gain more from convincing us that we’re sleep deprived than the folks who sell Ambien and CPAP machines?
But Americans toward the end of the 19th century were also worried about their sleep. After the Civil War, many were moving off the farm and into the city, where life was more stimulating, and both faster paced and more sedentary, than on the farm. A widely held view was that civilization was evolving faster than the human organism could keep pace with, and good sleep was falling by the wayside.
Are we living in a similar climate today? Do the dire warnings about insufficient sleep fit in with general concerns about the pace of our 24/7 lives, and do they likewise reflect anxiety about social changes and/or fear that we can’t keep up?
I’d like to know what you think.