This is a good question! To say that one would shine light on her vagina might be misleading, depending on who you're talking to. It's probably better to think of the location to shine the light on as on the abdomen, where the ovaries are located. This would prevent people from misinterpreting it as "shine the light on the entrance of the vagina." The light wouldn't penetrate deep enough to reach the ovaries if you did that. Some things to take into consideration are the distance between the surface of the skin and and actual ovaries, and the actual biological mechanisms behind the production of estrogen. It could very well be a different story from testosterone production in the testicles. Biology is very complicated and unfortunately we can't safely say without knowing some important, specific information.
RE: Red Light On Your Testicles Boosts Your Testosterone Levels