[A change in the reflex excitability of spinal motoneurons during daytime sleep in newborn infants].

Studies have been made on monosynaptic reflexes elicited by the electrical stimulation of the ulnar and peroneal nerves (H-reflexes) in 5-7-day infants during sleep and in the awake state. During the orthodox stage of sleep, which is characterized by slow oscillations in EEG and by synchronous respiratory movements of the thorax and abdomen, the amplitude of H-refelexes was the highest, variation coefficient being the lowest. During paradoxical stage of sleep, characterized by desynchronized EEG, the presence of rapid movements of the eyes and by asynchronous respiratory movements of the thorax and abdomen, the amplitude of H-reflex comprised 25-40% of this parameter during the orthodox sleep, variation coefficient exceeding 100%. In the awake state, the amplitude of H-reflexes was equal to 60% of that during the orthodox sleep.