The color of light could have a significant impact on the way the brain's clock measures the time of day.
The study is the first to provide a neuronal mechanism for how the internal clock measures the changes in light color present at dawn and dusk, PLOS reported. To make their findings a team of scientists looked at light color present at different times of day to determine if it could be used to tell the time. The findings showed that at twilight, the light is much bluer than it is during the rest of the day.
The researchers also recorded electrical activity from the brain clock while mice were shown a variety of visual stimuli, revealing many of the brain's neurons responded more strongly to changes in color than brightness. They also simulated an artificial sky that replicated the natural light color changes, and found nocturnal animals that were exposed for more than a month had the highest body temperatures just after dusk, when the sky was the darkest blue. If only the brightness of the sky was changed (with no light color change) the mice became more active after dusk, suggesting their biological clock was not working properly.
"This is the first time that we've been able to test the theory that [color] affects our body clock in any mammal. 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 study leader Timothy Brown from the Faculty of Life Sciences. "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 travellers wanting to [minimize] jet lag."
The findings were published in a recent edition of the journal PLOS Biology.