Virtually every type of sleep problem occurs in alcohol-dependent patients. Typically, these individuals take a longer time to fall asleep and show decreased sleep efficiency, shorter sleep duration and reduced amounts of slow wave sleep when compared with healthy controls. Their sleep patterns are fragmented, and the typical time course of electroencephalogram (EEG) delta wave activity is severely disrupted. The amount of rapid eye movement (REM) sleep may be reduced or increased. Sleep changes can persist during months or years of abstinence, and recent studies indicate that certain alterations in sleep architecture, as well as subjective sleep complaints, predict relapse to alcoholism. The mechanisms of action of short and long term alcohol administration on sleep are incompletely understood. They may arise from an interaction with gamma-aminobutyric acid (GABA), serotonin (5-hydroxytryptamine; 5-HT), adenosine or other neurotransmitter systems. While only a few pharmacological and nonpharmacological strategies to improve or normalise disturbed sleep in individuals who have recovered from alcoholism have been studied, the use of benzodiazepines, other hypnosedatives or selective serotonin reuptake inhibitors is not recommended. Therapies include sleep hygiene, bright light therapy, meditation, relaxation methods, and other nonpharmacological approaches. Further studies are needed to clarify the relationship between sleep, sleep abnormalities and alcoholism, and to establish new approaches to improve sleep in alcohol-dependent patients and to prevent withdrawal reactions that affect sleep during abstinence.