If you’ve ever gone camping, you’ve probably been surprised at how early you get tired in the evening. Turns out, there’s a biological reason why we tend to go to sleep early when among nature – and that the artificial glow from lamps, computers and cellphones deep into the night may not be healthy in the long term.
A recent study published in the medical journal Current Biology found that the more time volunteers spent outdoors, the more their circadian rhythms synchronized with the rising and setting sun.
The study’s researchers sent volunteers camping for a week in Colorado, during which the only sources of light allowed were the sun and campfire. The result? Their sleeping and waking patterns “all shifted to an earlier time,” said Kenneth Wright, a researcher from the University of Colorado in Boulder. “After exposure to the natural light dark cycle, melatonin levels were low just before the volunteers woke up, suggesting our brain is starting to promote wakefulness after we have been exposed to these natural cues.”
Melatonin is a hormone that helps regulate our sleep-wake cycle, and is influenced in part by photoreceptors in the retina, which explains why darkness causes us to be sleepy.
It’s in the Wavelength
Scientists have long suspected that artificial lighting could negatively affect our health, including contributing to later sleep schedules and problems waking up early in the morning. Light produced by blue wavelengths, in particular, has been shown to suppress melatonin the most. Incidentally, today’s energy efficient bulbs and electronic screens – TVs, computers, smartphones, etc. – emit more blue light.
At the University of Basel in Switzerland, scientists found that volunteers who were exposed to an old-style fluorescent monitor (with very little blue light) had higher-rising melatonin levels throughout the evening, versus levels measured when they were exposed to LED light, which had twice the levels of blue.
At the same time, researchers found that exposure to the LED light increased memory in the volunteers. This suggests that artificial blue light may help us become more alert, but ultimately at the expense of getting enough rest later.
Ban the Blue
Eliminating artificial light from our lives is, obviously, not feasible. Neither is going camping all the time. (Although I highly recommend camping as a great way to “unplug” from day-to-day stressors.) But there are a few things you can easily do to reduce your exposure to types of artificial light that may be affecting your circadian rhythm:
Reduce screen-staring activities (e.g., watching TV, reading on your computer or cellphone) before you go to sleep at night. Some tablets have special screens that purport to be better for the eyes, especially for reading
During the day, increase your exposure to natural sunlight; open your office window and/or choose natural light over artificial sources of light whenever possible. Added bonus: You’ll get a nice dose of vitamin D!
Keep your bedroom as dark as possible when sleeping
If you’re used to having a nightlight, consider using a red bulb; red light has been shown to suppress melatonin the least
Mind your health,
Dr. Keith Black