A phase II, double-blind RPCT showed that an 8-week melatonin treatment in women suffering from endometriosis (n = 40, age 18–45 years) significantly reduced daily pain (Δ = −39.8%) and dysmenorrhea (Δ = −38.01%), and also reduced the concentrations of brain derived neurotrophic factor (BDNF) by a mechanism distinct from that one alleviating pain [51]. This evidence concerns the gene BDNF and endometriosis.