Human auditory steady state evoked potentials during sleep.

The human auditory steady state evoked potentials were recorded during all-night sleep in 10 subjects. The effects of stimulus rate and intensity on these potentials were measured using on-line Fourier analysis. The amplitude of the response was greatest at stimulus rates of 30 to 50/sec. Although the response amplitude was lower during sleep, the rate at which the amplitude was greatest did not change between sleep and wakefulness. As the intensity was increased above threshold, the amplitude of the response increased linearly. The responses recorded during wakefulness showed a larger amplitude change with increasing intensity than during sleep. The estimated thresholds for the responses, however, did not differ significantly between wakefulness and sleep.