A while back, GFR reported on a study that found the scent of males blocks pain. Namely, proximity to a male researcher, or even clothing worn by a man, heightened the stress level of the rodents, which caused them to produce more corticosterone, which dulls the pain response. Scientists now think that ultraviolet radiation causes a similar response in humans, producing endorphins that block pain and make people feel good. So it seems that our love for sunlight is about a lot more than getting a tan.
In a study published in Cell, researchers from Boston’s Brigham and Women’s Hospital and Massachusetts General Hospital did UV radiation experiments on mice. They shaved a bunch of the rodents, and for six weeks let them soak in a moderate amount of UV rays (about 30 minutes a day), measuring their levels of beta-endorphins and their responses to pain. Their beta-endorphins were much higher than those of the mice that weren’t exposed, and they also had a higher resistance to pain. The team also let the mice choose whether to hang out in a brightly lit cage or a dark one. Since mice are nocturnal they generally chose the darkness, but the UV-exposed subjects were all for the light.