Responsiveness to stimulation during paradoxical sleep in infants

11 healthy children were repeatedly studied during 2 sleep cycles in 2 sessions at 2,6, 12 and 20 wk of life. Three acoustic stimuli, light and tactile stimulus were applied in a randomized order in intervals ranging randomly from 30 to 120 sec. Continuous polygraphic recordings were made of respiration, REMs, EEG and EMG of biceps and triceps brachii. The effect of stimuli on the length of paradoxical sleep, REMs and EMG was assessed. There were age-related changes in the number of REMs after stimuli. At 2 and 6 wk no stimulus elicited any change. At 12 wk the children responded with an increased number of rapid eye movements to acoustic stimuli, at 20 wk they responded to acoustic stimuli and light. The conclusion is that, as far as REMs are concerned, responsiveness during paradoxical sleep changes with age. There was a difference in the incidence of EOG responses and EMG responses. These findings show that it is not possible to assess responsiveness in infants during PS by one measure only.