Alcohol can have a significant impact on sleep and sleeping patterns. Under the influence of alcohol, the quantity of rapid eye movement (REM) sleep decreases and Stage 4 sleep increases, creating the impression that one has slept more soundly under the influence of alco- hol.

Excessive use of alcohol disrupts the natural pattern of sleep, so that chronic alcoholics who have completely abstained for extended periods of time have been shown to exhibit abnormal sleep patterns. It has been speculated that the disrup- tion of sleep patterns—particularly the reduction of REM sleep (often associated with dreaming)— by alcoholism results in irreversible brain damage.