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Scientists from Tel Aviv University have found that sunlight increases the production of sex hormones.
She first tested mice by exposing their skin to ultraviolet light. As a result, their production of testosterone, estrogen, progesterone and other hormones increased, and this affected mating behavior. Moreover, the level of aggression in males also increased.
Then they were tested on humans – however, on a sample of only 32 people. All participants noted an increase in sex drive and aggression. Laboratory tests have indicated an increase in testosterone levels.