A number of past studies have found that exposure to blue light later in the day may disrupt one’s sleep pattern, making it difficult to fall and stay asleep. New research out of the University of Manchester challenges those studies, asserting that blue light filters in the evening may actually make it harder to fall asleep by exposing humans to unnatural levels of warm light during a time of day when natural light is dim and cold.
The Sun obviously provides humanity with bright, warm light; it covers the orange-yellow hues we’d otherwise get from fire or, in modern times, ‘candle fire’-colored light bulbs. During the nighttime, however, this warm bright light is replaced with the dim, cold white light from the Moon, naturally exposing people to something similar to the ‘blue’ wavelengths emitted by many types of artificial lighting.
This natural transition from warm to cool light plays a role in regulating our sleep cycles, the latest study argues. Blue light filters like the kind found on most tablets and smartphones may actually be more disruptive to sleep patterns than non-filtered light, the researchers say.
Dr. Tim Brown explains:
We show the common view that blue light has the strongest effect on the clock is misguided; in fact, the blue colours that are associated with twilight have a weaker effect than white or yellow light of equivalent brightness … Our findings suggest that using dim, cooler, lights in the evening and bright warmer lights in the day may be more beneficial
This study involved exposing mice to lighting that could have its color adjusted without changing its brightness. When it came to exposure to yellow and blue light of the same level of brightness, the bluer colors were found to have lesser effects on the body’s internal clock compared to the yellow colors. The perception of light colors was ultimately found to play a role in body clock regulation.