Sleep experts are quick to blame bright street lights, TVs and the ever-distracting smartphone as the reasons why nearly one-third of U.S. adults don’t clock enough sleep on a regular basis. (For good reason ― some types of light can seriously mess with the body’s ability to wind down before sleep.)
But a new study published in the journal Human Biology this month suggests that even without distractions from artificial light sources and other modern technology, human sleep patterns can still be far from ideal.
A group of researchers, most of them from Duke University, tracked the sleep patterns of people living in a Madagascar farming village without electricity and few other sources of artificial light. The data showed the villagers slept less than a similarly sized group of people of the same ages in the U.S. and another similar group in Italy. And their sleep quality was actually worse.
But there’s a catch: The people in the rural community had stronger, more consistent circadian rhythms, which other research has linked to better health overall.
“This is proof in concept that, in traditional human populations with greater exposure to their environment, you can have a strong circadian rhythm and poor, short sleep at the same time,” study co-author David Samson, a senior research scientist in evolutionary anthropology at Duke University, told The Huffington Post.
That’s a significant finding, considering having a more consistent circadian rhythm (one that isn’t disrupted by things like irregular shift work and jet lag) has been linked to lower risks of developing memory problems, heart and metabolic diseases and some cancers.
Smartphones aren’t the only reason our sleep gets interrupted.
For the study, the researchers tracked the sleep of 21 adults in the rural farming village of Mandena in northeastern Madagascar for 292 nights total. Though some people in Mandena have generators or solar panels, the village itself has no infrastructure for electricity, which means that most people rely on cooking fires, kerosene lamps, a few battery-powered flashlights or the moon and stars for light after the sun goes down.
The villagers wore watch-like trackers that monitored light and movement, recording nightly sleep as well as daytime naps. Nine of the individuals were also tracked for a night using polysomnogram tests, which record electrical activity in the brain and muscles and provide more accurate measures of sleep stage and quality.
Compared to similarly sized groups of adults of approximately the same ages in both the U.S. and Italy, the villagers from Mandena slept for less time and had poorer sleep across all other quality measures the researchers tracked.
The villagers typically slept sometime between the hours of 7:30 p.m. (about two hours after sunset) and 5:30 a.m. (about an hour before sunrise) ― but only spent an average of six and a half hours per day truly asleep, including daytime napping. The U.S. group slept for approximately seven hours per night and the Italian group for approximately seven and a half hours per night.
The time residents of Mandena spent awake at night was three times as much as the time the U.S. group was awake, and nearly seven times as long as the Italian group.
The Mandena villagers also took longer to fall asleep and had more fragmented sleep than the Italian or American cohorts. The researchers suspect this is because they often shared rooms and beds with other people, and many houses have bamboo walls and tin or thatched roofs that don’t block outside noise like their neighbors’ socializing, children crying or animal noises.
Additionally, the polysomnogram tests revealed the villagers spent approximately half as much time in deep and rapid-eye-movement sleep (the restorative stages of sleep when individuals dream and our brains recharge) compared to the average Western adult in lab-based studies.
“There has always been a trade-off between sleeping and doing other things -- socializing, foraging for food, learning new skills.”- David Samson, a senior research scientist in evolutionary anthropology at Duke University
But when researchers measured how much the timing of Mandena villagers’ activities varied from day to day (according to the activity-tracker data), they found locals’ activity patterns were much more consistent and less fragmented than the activity patterns of a completely separate group of European students whose data had been collected in previous study.
And when residents of Mandena were asked “Are you happy with your sleep?” 60 percent of them answered “yes.”
Mandena, Madagascar, is a small rural community of approximately 4,000 people that sits adjacent to the Marojejy National Park (shown in the map below).
Spending more time outside may help our health.
The research findings were surprising, said Samson, whose team had expected the villagers in Mandena to sleep longer and better because they lacked the nighttime distractions of modern technology ― television, social media and artificial lighting. But the data showed they slept fewer hours and it was poorer quality.
But, the Mandena people appear to make up for lost and poor slumber with a more regular sleep routine and by spending a lot of time every day outside, Samson said ― evidenced by the fact that their circadian rhythms were more consistent.
“As a species, we’ve been tempted to skimp on sleep long before the advent of modern technology. There has always been a trade-off between sleeping and doing other things (socializing, foraging for food, learning new skills),” Samson said.
The data from this study is evidence that even without smartphones, those temptations sometimes win.
But, he added, most of those distractions aren’t as harmful to our bodies as spending a lot of time in front of artificial light in the evening, which can wreak havoc on our circadian rhythms.
The researchers did not collect enough information in this study to publish data about the villagers’ other health outcomes, some of which could potentially be linked to circadian rhythm problems. But the researchers plan to do so in the future. This work is part of a larger health project that aims to investigate whether groups of people who are exposed to less artificial light throughout the day ― and particularly at night ― do in fact have better health outcomes, Samson said.
The bottom line for people living in technology-saturated societies is that having a consistent routine can help your circadian rhythm even if you nap during the day or don’t sleep soundly at night, Samson said.
That means try to wake up, go to sleep, eat and schedule the most active parts of your day at the same time each day.
Getting outside is also important and might help counteract the negative effects of not getting great sleep, Samson said. “You shouldn’t hide away in comfortable climate- and light-controlled buildings all day.”
This article has been updated with more specific information about the types of data not collected by the researchers.
Sarah DiGiulio is The Huffington Post’s sleep reporter. You can contact her at firstname.lastname@example.org.