Viewing bright light early in the day can increase estrogen and testosterone in individuals with ovaries, and increase testosterone and estrogen in parallel in individuals with testes or supplementing with testosterone.

“viewing bright light early in the day, because of dopamine's effects, is going to promote more estrogen and subtle increases in testosterone, whereas if you're somebody who starts off with more testosterone and lower estrogen, so somebody presumably who has testes or maybe you're supplementing with testosterone through other sources for whatever reason, bright-light viewing is going to increase testosterone and estrogen in parallel, but you're still going to maintain the ratio of testosterone to estrogen”