In terms of prostate cancer, melatonin showed antiproliferative action on human prostate cancer cells.35 Independent of melatonin, increased levels of androgens, that can play a role in the development of prostate cancer, were observed among night shift workers compared with day workers.36 Additionally, strong evidence of a positive association between shift work and elevated prostate-specific antigen levels was documented in the National Health and Nutrition Examination Survey (NHANES) study indicating that shift work would likely increase the risk of prostate cancer.37 This evidence concerns the gene KLK3 and prostate carcinoma.