Since the invention of the light bulb, humans have drifted further and further from their natural sleep patterns. Artificial light tricks the brain into believing it is always daytime, putting the body in a constant state of heightened alert. Now, a new study of rural life in South America confirms that societies without the incessant glare of iPads and TVs do, indeed, align their sleep to the rising and setting of the sun.
The Centers for Disease Control and Prevention estimates that roughly one-third of Americans suffer from sleep deprivation and at least a quarter say it's affecting their ability to work. And the problem is getting more severe; as email and other electronics become a perpetual part of night-time work, we get less and less sleep.
Looking for a solution, some researchers have taken to monitoring cultures that are less technology-dominated. A new study on the lives of people in the rural town of Baependi, Brazil, finds that the citizens' sleep cycle is neatly aligned with the setting and rising of the sun. Basically, researchers found that this particular group of Brazilians are more likely to fall asleep shortly after sundown—9:20 a.m.—and wake up with the sunrise, around 6:30 a.m. By comparison, those in London typically fall asleep long after sunset—11:15 p.m.—and rise to an already bright sky, at 8:30 a.m.
“In big cities, the availability of cheap electricity has brought us both artificial lighting and a multitude of other electronic devices that compete with us going to sleep at night,” explains Malcolm von Schantz, one of the study's authors. “The people of Baependi, particularly those in the countryside, maintain a much stronger link with the solar rhythm.”
The brain uses light as a signal to self-regulate for sleep and work. Without exposure to a bright sun, or a spectrum of light that mimics the sun, workers drag on through the day in dreadful sleepiness.
Unlike the more ancient form of light—that is, fire—light emitted from a screen contains the blue spectrum of light that can be found on a clear sunny day. Our brains therefore associate the blue spectrum with the work day and, in its presence, suppress the melatonin, the chemical involved in sleep. Prior to the Industrial Revolution, the only time humans were exposed to the blue spectrum of light past sundown was with a bright, full moon.
Once as dim and far away as the surface of the moon, electronics have brought the blue spectrum of light closer and closer to our eyes. To be sure, one study found that people who read on a phone or tablet before bed have significantly worse deep sleep.
Studying how individuals' sleep cycles naturally sync with the solar rhythm can help technologists offset the deleterious effects of electronics. For instance, start-up founder Michael Herf designs a popular software, f.lux, that dims the brightness of electronics with the setting of the sun, tinting screens a fire-orange hue.
Speaking with me at the TED conference in Vancouver last week, Herf explained that getting blue light in the morning is as important as avoiding it at night. Commuters who wake up before dawn and then spend all day in poorly lit buildings never get the proper signals for alertness.
The brain uses light as a signal to self-regulate for sleep and work. Without exposure to a bright sun, or a spectrum of light that mimics the sun, workers drag on through the day in dreadful sleepiness. Indeed, a recent study in PLoS One found that blue light therapy can be a good substitute for coffee.
Understanding how much light is necessary for natural drowsiness and alertness can help innovators like Herf design electronics that support—rather than wreck—our sleep cycles.