American scientists from the University of Washington in Seattle have developed a device that resets the body's biological clock, also known as circadian rhythms. The study was published in the scientific journal Journal of Biological Rhythms (JBR).
Circadian rhythms are dependent on the daily cycle. They stimulate circuits in the eyes that communicate with the brain. Using this information, the brain produces the hormone melatonin, which helps us fall asleep at night.
Many health and mood problems are attributed to circadian rhythms that are out of sync. This asynchrony is triggered by seasonal changes, lack of natural light, night shift work, and flying across time zones.
People who spend many hours a day under artificial light often suffer from disruptions in circadian rhythms and a lack of melatonin, causing sleep disturbances.
In the new study, the researchers tested three light sources with bulbs of different colors. The first emitted visible light at 500 lux (a brightness suitable for typical office spaces). The second used a short-wave blue LED that activated melanopsin (the photopigment responsible for the eyes' sensitivity to light). The third source was equipped with an LED with blue and orange wavelengths alternating 19 times per second.
Scientists exposed volunteers to light from various devices and studied the concentration of melatonin in their bodies using saliva tests.
The third LED, alternating blue and orange shades of light, turned out to be the most effective. It allowed shifting the phase of melatonin production by 80 minutes. Blue light accelerated hormone production by 40 minutes, and regular white light – only by 2.8 minutes.
According to scientists, the combination of orange and blue light can influence the body's circadian rhythms due to the fact that these are the shades we typically see in the sunset sky at the end of the day.
