NEW YORK: When twilight sets in, it may not be the dimming light that clues you in to the evening hour — instead, it could be that blueish glow in the sky. According to a new study of mice, its light color, rather than brightness, that may account for how a number of mammals biologically keep track of time.
The discovery could also have implications for human body clocks and sleep cycles, because human sleep is reliant on a 24-hour cycle of hormone release that is triggered by light.
In the study, published in the journal PLOS Biology, researchers from the University of Manchester were able to distinguish between the roles of light color and light intensity in the ability of mice to recognize the time of day. The study also revealed the prevailing strength with which the mice responded to color as opposed to radiance.
“This is the first time that we’ve been able to test the theory that color affects our body clock in any mammal,” lead study author Dr. Timothy Brown said in a statement. “What’s exciting about our research is that the same findings can be applied to humans. So, in theory, color could be used to manipulate our clock, which could be useful for shift workers or travelers wanting to minimize jet lag.”
After analyzing the differences in light colors associated with sunrise and sunset, the researchers found that blue proved more dominant during twilight than any other time of day. They then measured the electrical activity associated with the rodents’ body clocks during a visual stimulation experiment, and confirmed that the mice reacted the most dramatically to yellow and blue hues and to color more than light intensity.
