Alcohol use and sleep have a complex relationship.[1] Whilealcohol may initially induce drowsiness, it can disrupt sleep quality and exacerbatesleep disorders in the long run. Duringabstinence, sleep disruption is one of the greatest predictors ofrelapse.[2]
Moderate alcohol consumption 30–60 minutes before bedtime results in disruptions in sleep maintenance and sleep architecture that are mediated byblood alcohol levels.[3] Disruptions in sleep maintenance are most marked once alcohol has been completelymetabolized from the body. Under conditions of moderate alcohol consumption where blood alcohol levels average 0.06–0.08% and decrease 0.01–0.02% per hour, an alcohol clearance rate of 4–5 hours would coincide with disruptions in sleep maintenance in the second half of an 8-hour sleep episode.[3] In terms of sleep architecture, moderate doses of alcohol facilitate "rebounds" inrapid eye movement (REM) andstage 1 sleep; following suppression in REM and stage 1 sleep in the first half of an 8-hour sleep episode, REM and stage 1 sleep increase well beyond baseline in the second half. Moderate doses of alcohol also increaseslow wave sleep (SWS) in the first half of an 8-hour sleep episode.[3] Enhancements in REM sleep and SWS following moderate alcohol consumption are mediated by reductions inglutamatergic activity byadenosine in thecentral nervous system.[3] In addition, tolerance to changes in sleep maintenance and sleep architecture develops within 3 days of alcohol consumption before bedtime.[3]
Low doses of alcohol (one 360.0 ml (13 imp fl oz; 12 US fl oz)beer) are sleep-promoting by increasing total sleep time and reducing awakenings during the night. The sleep-promoting benefits of alcoholdissipate at moderate and higher doses of alcohol (two 12 oz. beers and three 12 oz. beers, respectively).[4] Previous experience with alcohol also determines whether or not alcohol is a "sleep promoter" or "sleep disrupter." Under free-choice conditions, in which subjects chose between drinking alcohol or water, inexperienced drinkers were sedated while experienced drinkers were stimulated following alcohol consumption.[5] Ininsomniacs, moderate doses of alcohol improve sleep maintenance.[6]
Sleepiness influences the severity of alcohol consumption. Conditions ofsleep deprivation encourage more episodes of alcohol consumption.[3] Increased alcohol consumption during the winter months for Northern climate residents is attributed to escalations in fatigue.[7]
Sleep andhormonal disruptions following withdrawal from chronic alcohol consumption are the greatest predictors of relapse.[2] During abstinence, recovering alcoholics have attenuatedmelatonin secretion in the beginning of a sleep episode, resulting in prolonged sleep latencies.[8] Escalations incortisol andcore body temperatures during the sleep period contribute to poor sleep maintenance.[8][9] Abstinent alcoholics tend to have lighter, more fragmented sleep than normal control subjects. Research indicates that it may take as long as one to two years for sleep to return to normal in abstinent alcoholics and that for some it may never return to normal.
