EEG measures of functional tolerance to alcohol.

The literature suggests that alcohol ingestion produces characteristic alterations of sleep physiology and evoked response in alcoholics. Studies of alcohol withdrawal indicate that for some alcoholics residual functional tolerance remains apparent for an indefinite period. Low amounts of slow wave sleep (SWS) appear to be one of the physiological concomitants of the residual tolerance. Visual evoked responses were recorded from two small groups of inpatient alcoholics identified as normal or low SWS during a sober period. Alcohol ingestion produced no significant changes of evoked response parameters. Alcohol withdrawal produced significant augmentation of early component amplitude for the low SWS group only. These data suggest that low SWS and augmented primary component amplitude may be physiological correlates of functional tolerance to alcohol.