WELLNESS
04/24/2015 09:06 am ET Updated Dec 06, 2017

Our Body Clocks May Tell Time More Accurately By The Color Of Light

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, it's 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.

Next, the researchers created an artificial sky and placed the mice beneath the simulation for several days, monitoring their body temperatures to account for the changes in their internal body clocks. Since mice are nocturnal, their temperatures spiked as expected as nighttime set in and the sky shifted into a darker blue tone.

However, when the researchers manually changed the artificial sky's brightness without adjusting the color of the backdrop, the mice proved more active before dusk, revealing that their body clocks were out of sync with the day-night cycle of their environment. While the increase in light should have made them more restful, the darker blue acted more dominantly in making them active.

While this groundbreaking study is the first of its kind, there is some previous research into light color affecting human sleep cycles. For example, we know blue light emissions can disturb sleep, and research has even found that selecting night lights that are reddish in color can help minimize additional sleep-cycle disruptions if a person has to get up in the middle of the night.

To help your body subscribe to its natural sleep cycle, check out this suggested schedule for winding down at night:


Infographic by Jan Diehm for The Huffington Post

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