[The development of sleep phases and thermoregulation in the early ontogeny of rats].

In newborn Wistar rats, studies have been made on the EEG parameters of the cortex and hippocamp, as well as on the dynamics of temperature in the brain and cervical muscles in the awake state, quiet (QS) and active (AS) sleep. With respect to most of the investigated parameters, QS and AS correspond to slow wave and paradoxical sleep of adult animals. Stable EEG patterns in the form of synchronization of bioelectrical activity during slow wave sleep or desynchronization during paradoxical one were found in rat puppies beginning from the 7th day. The increase in the brain temperature together with the decrease in muscle temperature during separate moments of AS, as well as the decrease of both temperatures during QS were observed already in 4-day rat puppies. The data obtained suggest that close correlation between thermoregulation and sleep is formed in mammals already at early stages of postnatal life.