A most interesting (and very complex) research paper has discovered another way in which sun exposure may contribute to health and also demonstrates a mechanism by which the skin communicates with the brain.[i]
The researchers’ experiment involved using UVB radiation from a sunlamp on the skin of mice and then measuring, among other things, the influence of a signaling mechanism from the skin to the hypothalamus, which increased the quantity of a peptide hormone, known as alpha-melanocyte stimulating hormone (a-MSH). The hormone is important in stimulating pigmentation (melanin) production in the skin. It also has a role in energy balance, feeding behavior and energy homeostasis.[ii]
When the mice were radiated with UVB, their hypothalami received a neural signal which caused them to produce both a-MSH and b-Endorphin, which we all know to be one of the feel-good hormones, also called a reward hormone or natural “upper.” The researchers described this effect as being anorexigenic, meaning that it caused a loss of appetite. It seems that a loss of appetite combined with a natural “upper,” would be a good recipe for effective weight-control. Keeping the metabolism high is important to controlling weight, and the writers made an interesting statement regarding metabolism to end their paper:
“In conclusion, we have established a new paradigm of UVB induced activation of POMC signaling in the hypothalamus with attendant increases of a-MSH and b-END in the plasma which opens up exciting areas of research on the communication between skin and brain and that suggests a role for UVB in regulation of body metabolism.”
This was a recondite paper that took a lot of digging to get through. This would be my translation: “Get some sun exposure or sun lamp exposure; it will increase endorphin levels, rev up the metabolism and help you stay slim and healthy.”
Be safe while you sun, and remember that most sunscreens will stop UVB from doing its job.
There seems to be no end to the positive influence of sunlight on human health and well-being.
[i] Cezary Skobowiat and Andrzej T. Slominski. Ultraviolet B stimulates proopiomelanocortin signaling in the arcuate nucleus of the hypothalamus in mice. Experimental Dermatology, 2016, 25, 120–123.
[ii] Wikipedia. Alpha-Melanocyte-stimulating hormone. https://en.wikipedia.org/wiki/Alpha-Melanocyte-stimulating_hormone. (accessed February 12, 2016)