KLK3 and prostate cancer: 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