[Electroencephalographic study of sleep in Sea of Azov porpoises].

ECoG of both hemispheres, EMG of neck muscles, ECG and respiration rate were recorded in 3 free swimming Black Sea porpoises. The sleep characteristics in the porpoises were similar to those in the bottlenose dolphins which have been investigated earlier. Unihemispheric slow sleep was the main type of the porpoise sleep. Paradoxical sleep has not yet been found in them. All ther types of the porpoise sleep occurred during swimming and therefore could not serve to spare energy and to immobilize the animal. The experiments with nembutal and diazepam administration suggest that the functional necessity of the unihemispheric sleep results from the impossibility of maintaining dolphins' respiration during bilateral delta-sleep.