A pair of recently published studies suggest that our circadian rhythm can be quickly recalibrated, which may improve sleep cycles, energy levels, and seasonal depression.
As much as new technology, and easily accessible technology, improves some aspects of our lives, it can also take a toll on our health. The ubiquitous screens in our pockets, on our laps, on our desks, and in our entertainment centers, coupled with the near-constant onslaught of artificial lights at all hours of the day, can wreak havoc with our sleep cycles, which in turn can affect our productivity, our performance, and our moods.
In the last few years, the evidence that blue wavelengths of light - such as those produced from our screens and some energy-efficient lighting sources - can impact our health negatively has been brought to light (!), but many of us are so hooked into our modern lifestyle habits that avoiding screens and lights after dark can seem virtually impossible. However, some new insights into the effects of light on our internal clocks points to a remarkably simple method of recalibrating our sleep cycles.
A paper recently published in the journal Current Biology, consisting of two papers documenting experiments that measured the levels of the hormone melatonin (which regulates sleep and wakefulness) in people who spent either a full week, or just a weekend, camping out away from artificial lights, suggests that our circadian rhythm can be reset with a regimen of exposure to "only natural light (i.e., sunlight, moonlight, and campfires; no flashlights, no personal electronic devices)."
According to lead author Kenneth Wright, an integrative physiology professor at CU Boulder, “These studies suggest that our internal clock responds strongly and quite rapidly to the natural light-dark cycle.”
“Living in our modern environments can significantly delay our circadian timing and late circadian timing is associated with many health consequences. But as little as a weekend camping trip can reset it.” - Wright
One of the studies called for a set of 14 volunteers, 9 of whom went camping in Colorado's Eagle's Nest Wilderness over a summer weekend, while the other 5 stayed home. After the weekend camping trip, the volunteers had their saliva tested, which revealed that the rise of melatonin in those campers had shifted almost an hour and a half earlier, which is a sign that their 'biological day' had shifted to be more in line with natural light-dark cycles.
In the second study, volunteers went camping for a week in the Cache La Poudre Wilderness (Colorado) around the winter solstice, when the hours of daylight are the shortest, and then had their melatonin levels tested hourly over the course of 24 hours immediately after they returned. Those volunteers saw their melatonin levels begin to rise 2.6 hours earlier, in part due to their exposure to some 13 times as much light during the winter day as during their regular environment, as well as their earlier bedtime and longer sleep cycle while camping.
"Weekend exposure to natural light was sufficient to achieve 69 percent of the shift in circadian timing we previously reported after a week’s exposure to natural light." - Wright
Simply getting away from artificial light for the weekend wasn't enough to keep those volunteers' sleep cycles on track long-term, as jumping right back into modern time-shifted regimens, such as staying awake long past dark while being exposed to artificial lighting will again take its toll. However, by sticking to the 'new' natural light-dark circadian rhythm after such a reset, research suggests that the jet-lag effect and and other negative impacts of our modern light-saturated environment could be minimized.
For those who can't, or don't want to, take a weekend out in nature to help recalibrate their internal clock, Wright suggested that "getting more bright natural light by day and shutting off smartphones and laptops well before bedtime" can help.
The results of the study may also help to create healthier work environments as well, through better design:
"Our findings highlight an opportunity for architectural design to bring more natural sunlight into the modern built environment and to work with lighting companies to incorporate tunable lighting that could change across the day and night to enhance performance, health and well-being." - Wright
The study, Circadian Entrainment to the Natural Light-Dark Cycle across Seasons and the Weekend, is available at Current Biology.