Color, Not Light Brightness Helps your Body Tell Time

An interesting new study has shown that the biological clock may actually tell time through changes in sunlight's color and not its intensity or brightness, as is usually thought.

The study conducted by researchers at the University of Manchester found that changing color of light as the day progresses can help the body better tell time rather than the frequently used brightness change. The findings were based on mice studies, which led researchers to conclude that it could also apply to humans.

Researchers exposed mice to different visuals and measured sensitivity of cells they identified as constituting the body clock. They found that the cells are more sensitive to color changes than brightness changes. Scientists then sampled the sky's color spectra changes, to create an artificial sky.

The mice were then placed under the artificial sky for many days as part of the experiment, when their body temperatures were noted. Given that they are nocturnal, mice body temperatures are highest just after nightfall.

Through body temperature readings, researchers found that mice bodies were able to sync with the circadian clock when the sky's color changed but not when brightness changes occurred. When researchers tinkered with brightness intensity they found the mice became active before dusk.

"This is the first time that we've been able to test the theory that color affects the body clock in mammals. It has always been very hard to separate the change in color to the change in brightness but using new experimental tools and a psychophysics approach we were successful," said Dr. Timothy Brown the study's lead researcher.

The study's findings have been published in the journal PLOS Biology.