[Alcohol, sleep and biological rhythms]

Alcohol reduces sleep latency but notably alters sleep structure: sleep is fragmented, particularly at the end of the night. Slow wave sleep duration is enhanced in the first part of the night and REM sleep duration and density are diminished. Alcohol withdrawal provokes inverse effects in alcoholic patients: sleep onset is delayed, slow wave sleep durations diminished and REM sleep duration is enhanced. REM sleep is associated with motor inhibition failure. Sleep remains disturbed in long term evaluations. Alcohol promotes the occurrence of sleep apneas and hypopneas. This effect persists in alcoholics after alcohol withdrawal. Sleep disturbances in alcoholism can be partly understood as the expression of amplitude diminution and phase advance of biological rhythms. Thus, the chronobiologic characteristics of alcoholics resemble those of depressives or the elderly.