Stage II sleep alters infants' short latency somatosensory evoked potentials

To evaluate the effects of stage II sleep on short latency somatosensory evoked potentials (SLSEP) to median nerve stimulation, we studied 16 normal infants from two to twelve months of age. SLSEP were recorded during waking and stage II sleep. Four channels of parasagittal EEG and behavioral observations were used to classify states. Compared with SEP in the waking state, cerebral potentials in stage II sleep were of much lower amplitude, even vanishing entirely in several infants. In addition, the change from waking to stage II sleep produced significantly longer latencies of the peaks N1, P1, and P2. We suggest performing SLSEP in infants in the waking state in order to assess cerebral somatosensory function.