The paper deals with the results of studies of the morphofunctional condition of neurons of the rats hypothalamus’ suprachiasmatic nuclei (SCN) under conditions of diverse duration of the photoperiod. It has been established that the diurnal rhythm of the morphofunctional activity of neurons of the hypothalamic SCN subjected to a prolonged exposure to light was essentially violated. Their higher activity, in contrast to rats exposed to ordinary lighting, was registered during the day light observation.
