Our circadian rhythm is controlled by light, via photoreceptive proteins called “opsins”, like neuropsin and melanopsin.
Humans possess photoreceptors, like neuropsin, in just about every surface and subcutaneous area of the body – adipocytes (fat), retina, testes, the epidermis (skin), hair follicles (in mice, but I’m sure will find them in us humans as well)…
Why did God or evolution design it this way? It’s because ultraviolet, visible, and infrared light ‘fuels’ the body. Light modulates, coordinates, and/or activates human biology. From immunity to form, circadian rhythm, behavior, and more. This is achieved through various hormones, neurotransmitters, endocannabinoids, and vitamin D. Humans, as with other mammals were designed to be naked under the sun, moon, and starlight, 24 hours a day, 365 days a year. Why then is it the norm and acceptable for the average American to spend 97% of their day indoors bathed in artificial light, made up of only a tiny spectrum of light – blue? Artificial light can’t duplicate Mother Nature, so the above-mentioned actions will be altered leading to negative consequences. Just about any disease or bad behavior can be brought on or made worse by lack of natural sunlight and in its place only receiving artificial “blue” light.
These photoreceptors are part of a family of proteins known as opsins. It is a photoreceptor protein sensitive to ultraviolet (UV) light. Most importantly, the photoreceptors specific to the epidermis (skin) operate independently of the eye and brain. This particular opsin is known as neuropsin.
This means that our skin can sense whether it is day or night. Our skin uses neuropsin to sense the light-dark cycle to keep time and play a part in our circadian rhythm.
“If you simulate taking the cultured skin from Seattle to Japan (by simulating the light changes across time zones), the skin figures out that the time zone has changed and adapts to the new time zone within days because of neuropsin.” Russ Van Gelder, professor, and chair of ophthalmology at the UW School of Medicine. Scientists discover skin keeps time independent of the brain. October 16, 2019.