Can melatonin supplementation reduce testosterone levels in men?

It’s been suggested that taking melatonin might lower testosterone levels in males. This idea stems in large part from some animal studies in which exogenously-administered melatonin reduced testosterone production.^[1] However, these studies used melatonin exposures of unclear physiological relevance, so their findings should be viewed with caution. Clinical trials on human men, meanwhile, have found that melatonin supplementation of up to 6 mg per night does not reduce testosterone levels.^[2][3][4][5]