A new study shows for the first time how the color of light can have a significant effect on our internal clocks, and how the brain applies it in relation to the time of day.
The University of Manchester study examines how changes in light during dawn and dusk can help humans and animals alike in figuring out the specific time of the day at the moment. Previously, it had been shown that changes in light intensity take place in sunrise and sunset, but the University of Manchester scientists had determined that twilight light is “reliably bluer” than it is in the daytime.
The researchers used several mice and subjected them to different kinds of visual stimuli, recording electrical activity from their brains. According to the study, many of the mice’s neurons were more sensitive to color change from blue to yellow than they were to brightness changes. An artificial sky recreating color changes and brightness was then simulated, and when the mice were placed under the sky for a number of days, their body temperatures had peaked right after dusk, just as the sky had become a darker blue; this is indicative of a normal body clock.
However, if only the sky’s brightness was changed, but not its color, the mice were more active before dusk, a sign that their body clock wasn’t optimized toward a normal day-night cycle. This allowed the research to be successful, proving that color does indeed affect a mammal’s body clock.
According to study head Dr. Timothy Brown, the findings on mice can also be applied to humans. “So, in theory, colour could be used to manipulate our clock, which could be useful for shift workers or travellers wanting to minimise jet lag,” he concluded.