We know that our bodies respond to changes in the intensity of light. Now researchers at the University of Manchester have showed that the color of the light also has a major impact on animals’ behavior and physiology, and how our body’s internal clocks measure the time of the day. The discovery is particularly useful for travelers and shift workers who want to minimize jet lag.
Brain clocks more sensitive to color than to light
Scientists show a neuronal mechanism on how our body clocks measure changes in the color of light that accompany dawn and dusk. Researchers led by Dr Timothy Brown discovered that during twilight, light is bluer than during the daylight hours. Findings of the study were published in the journal PLOS Biology.
To conduct the study, scientists exposed mice to various visual stimuli and recorded the electrical activity in their brain’s biological clock. They observed that a large portion of neurons was far more sensitive to changes in color between yellow and blue than changes in the intensity of light. The intensity of the light changes with the rising and setting of the sun.
Dr Brown and his colleagues then simulated an artificial sky, recreating the daily changes in intensity and color of light. Mice are nocturnal animals that become active after dusk. When placed under the artificial sky for many days, researchers measured the highest temperature in the bodies of mice just after dusk, when the sky became a darker blue. It suggests that their body clock was working properly.
The finding can also be applied to humans
But when the brightness of the artificial sky was changed, with the color remaining constant, these animals became more active before dusk. It indicates that their body’s internal clocks were not properly aligned to the day-night cycle. So, Dr Brown points out, the color of light can be used to manipulate our body’s internal clock to help those wanting to minimize jet lag.
He said the sensory mechanism for estimating time of the day is found in all mammals that are capable of color vision. These findings could be applied to humans, too.