The effects of selective sleep stage deprivation on the visual evoked potential

The purpose of the present study was to evaluate the role of REM sleep, delta sleep, and total sleep time in the processing of visual information as measured by the visual evoked potential (VEP). Six male college students spent two nights in the laboratory in each of four experimental conditions, with at least five nights of recovery time between each condition. The four conditions involved REM sleep deprivation, delta sleep deprivation, and control nights of either non-REM, or non-delta awakenings. VEPs, evoked by letter stimuli, were recorded from vertex and frontal electrodes on the morning after each experimental condition, and on four mornings after the subjects had slept at home (as a baseline). The subjects were required to respond to a "target" letter by pressing a microswitch, but to refrain from responding to other, non-targeted letters.

Comparison of the VEPs following each experimental condition revealed that those following REM deprivation and delta control nights were significantly different from those recorded following the other experimental conditions, and from baseline. The differences were primarily limited to the N100 component, and to EPs recorded at the vertex in response to targeted stimuli. The amplitude of the N100 was significantly greater following these two conditions. An additional difference was observed in the P300 recorded at the vertex following REM deprivation. In this case, REM deprivation decreased the amplitudinal difference between the P300 recorded in response to the target stimulus, and that recorded in response to non-targeted stimuli. Since there was a significant difference between targeted and non-targeted VEPs in every other condition, this absence of difference was considered to be meaningful.

The results appeared to indicate that a loss or decrease of REM sleep interfered with information processing as measured by the EP. However, since the REM deprivation condition (and the delta control condition) also produced a decrease in total sleep time, this may have contributed to the observed differences. Furthermore, a more parsimonious explanation for the results may be that REM deprivation produced an increase in cortical arousal and reactivity, and that this increased arousal in turn produced the changes in the VEP. This explanation of the results was shown to be consistent with previous research.