Industrial xenobitics, as well as endogenous damaging factors, such as L-homocysteine, are a well-known source of reactive oxygen species that disrupt biological processes. Among many others, luteinizing hormone releasing hormone synthesis and secretion mediated by a variety of neurotransmitters, which are under control of the hypothalamus and pineal gland, may be put in peril by reactive oxygen species. Their formation can be one of the reasons for the reproductive function shutdown in ageing as the generic response to the damaging factors independent of their nature. We review recent findings demonstrating the role of reactive oxygen species in disrupting the circadian signal originated in the main pacemaker of the organism, the suprachiasmatic nuclei of the hypothalamus, on its way to the hypothalamic areas responsible for the luteinizing hormone preovulatory surge.