For 30 minutes each morning, these men sat in front of a light box that exposed them to 10,000 lux of light. (For comparison, direct sunlight can reach up to 100,000 lux, and a cloudy day is about 1,000 lux.)
After two weeks, the men receiving the bright light treatment reported sexual satisfaction scores that were three times higher than when they began the experiment. (The guys in the other group showed only modest increases.)
Related: 3 Steps To More Testosterone
The bright light group also saw a boost in their testosterone levels - which is vital to increasing libido, says lead researcher Dr Andrea Fagiolini, of the University of Siena.
When your body is exposed to bright light, it produces more of a chemical called the luteinising hormone (LH). And more LH may lead to greater production of testosterone, Dr. Fagiolini says.
Related: Do You Have Low Testosterone? Take Our Quiz and Find Out
This doesn’t mean you can crank up your sex drive simply by rolling up the window shades: You should shoot for roughly the same intensity of light used by the study participants.
You can find that level in a personal light box, which you can purchase online and use at home.
Just make sure you talk to your doctor first. Before you get the go-ahead, he or she might test you for other problems like low testosterone, thyroid problems, or kidney disease, all of which can cause a drop in libido, too.