The true culprit, a growing number of sleep scientists believe, is something much more mundane: the ambient glow of artificial illumination emitted from our light fixtures, computer screens, and primetime TV shows.
The theory goes like this: We evolved to operate on a 24-hour cycle, based off of the reliable rise and set of the Sun everyday. Historically, our bodies were stimulated by these events occurring at roughly the same time daily, so they knew to do things like secrete the hormone melatonin (which aids in sleep) just before sunset, and reduce production of it just before sunrise. This and other biological patterns—known as our internal circadian rhythm—ensured a solid night of sleep and a wakeful morning, day in and day out.
Until the advent of electricity and other elements modern technology, that is, which brought artificial light into all hours of our nights. Our technology—and the increasing reliance on it for our jobs and studies in our labor- and service-based economy—also means that we spend most of our daytime inside, with less exposure to the sunlight needed to set our circadian clocks. As a result, many of us can’t fall asleep when we want to, have trouble sleeping through the night, and feel the opposite of refreshed when our alarm starts buzzing in the morning.
A new study, published yesterday in Current Biology, shows just how detrimental artificial light is to a healthy sleep cycle by testing the hypothesis in a new way. In the study, eight people spent a week camping in the Colorado Rockies without any source of artificial light. To a person, the time spent outdoors during day and night restored a natural sleep cycle, turning even night owls into early risers.
The research team, led by Kenneth Wright, the director of the Sleep and Chronobiology Laboratory at the University of Colorado at Boulder, first closely tracked the sleep habits of the participants, who had an average age of 30, for a week’s time as they went about their normal lives. Each participant wore a watch with sensors that measured their light exposure and when they moved, to indicate when they were sleeping. For one of the days, they also submitted frequent saliva samples, so the scientists could measure the levels of melatonin in their bodies over the course of the day.
Next, the participants were sent for a week of camping in the Eagle Nest Wilderness, forbidden from bringing any electronics that emit artificial light—even flashlights. They wore the same sensors, so the researchers could see their sleeping habits and natural light exposure during the week away.
When the research team looked at the data, they found that all eight participants steadily shifted towards a sleep schedule that more closely mirrored the setting and rising of the Sun. Those who’d been night owls before the camping period—staying up later and waking later—saw the most dramatic shifts in their sleep cycles. As a whole, the campers slept for roughly the same amount of time each night as before, but fell asleep two hours earlier and awoke–without alarm clocks–two hours earlier as well.
The scientists say two factors are at work. For one, eliminating exposure to artificial light after sunset allowed the participants to naturally increase their melatonin levels at the right time, promoting sleep. Additionally, being exposed to natural light all day—something few office workers or students experience on a regular basis—also helped to set their circadian clocks, and as a result, they naturally cut back melatonin levels just before waking, reducing levels of grogginess. For many people in the modern world, melatonin levels don’t drop until one or two hours after waking up, accounting for the extreme tiredness many of us feel when the alarm clock goes off.
How can you take advantage of the finding to improve your own sleep schedule? The researchers say that any increased level of natural light in your day—whether a walk in the morning, a lunch outside, or an opened windowshade—can help align your circadian rhythms more closely with the Sun. Minimizing exposure to artificial light and electronics once the Sun has gone down (dimming lights, and shutting off phones, TVs and tablets) can also make a huge difference.
Of course, to those for whom the research finding is absolutely no surprise—the solution to your sleep woes is much simpler. If you have the freedom (and if unlike this guy you don’t fear the daystar), get off your computer, leave your house, and go camping.