Visible light, oxidative stress, and reproduction: The protective role of melatonin.

Melatonin, a hormone produced by the pineal gland and reproductive tissues, regulates circadian rhythms, antioxidant activity, and fertility. Artificial light at night suppresses melatonin, leading to increased oxidative stress and compromised sperm and egg quality. During assisted reproductive technologies (ART), light exposure generates harmful reactive oxygen species (ROS), impairing gametes and embryos. Melatonin counteracts ROS, enhances antioxidant defenses, and improves embryo development, blastocyst formation, and implantation. This review examines melatonin's protective role in reproduction and how light exposure affects fertility. Understanding these mechanisms could enhance the success of ART and fertility treatments.