New research found that skin keeps time independent of the brain, suggesting that specific colours of light at certain times of day could influence how skin heals.
The same photoreceptors responsible for giving a chameleon the power to change its skin colour are also found in humans, and now they could play an important part in future medical treatment.
These photoreceptors are part of a family of proteins called opsins, which are most abundant in the retina of mammals and are responsible for colour vision and vision in dim light. While previous studies have suggested that mammals might express opsin proteins outside the eye, there was little information on what functions they might influence.
Now, a study published to Current Biology by researchers from the University of Washington School of Medicine has found that a type of opsin called neuropsin has been discovered in hair follicles in mice. Its purpose is to synchronise the skin’s circadian clock with the light-dark cycle, independently of the eyes or brain, and is the first discovered outside the eye in mammals.
This means that skin can sense whether it is day or night, even when it’s cultured by itself in a dish.
“If you simulate taking the cultured skin from Seattle to Japan by simulating the light changes across time zones, it figures out that the time zone has changed and adapts to the new time zone within days because of neuropsin,” said the study’s co-author Russ Van Gelder.
Previous research has shown that exposing mice to ultraviolet light in the early morning had a five-fold higher effect in initiating skin cancer when compared with the same light given in the late afternoon. This is because of circadian changes in the skin’s ability to repair DNA damage.
Richard Lang, co-lead investigator of the research, said: “Although our research is still underway, we hypothesise that specific colours of light at certain times of day will influence how the skin heals.”