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Sorry But That Nightcap Definitely Isn’t Helping You Sleep—and Could Hinder Recovery

Research shows a nightcap can mess with your REM cycle.

A new study shows that just one alcoholic drink, consumed about an hour before bed, can reduce REM sleep. 

Experts suggest cutting down on alcohol (or trying a period without it) to see how it affects your sleep quality. 

The connection between alcohol consumption and poor sleep is well established—previous studies point to booze shortening sleep duration, increasing odds of snoring, and leading to daytime sleepiness (even if it initially provides a sedating effect)—but why is it so problematic? New research published in the journal SLEEP suggests sleep quality suffers due to the way alcohol significantly reduces REM sleep, the type needed for adequate mental function.

Researchers looked at 36 participants of an in-lab sleep study, who drank either an alcoholic or non-alcoholic beverage about an hour before going to bed, for three consecutive nights on two different occasions. 

They found that when the alcohol was consumed, participants had notably less REM sleep compared to the nights when they drank the non-alcoholic beverage. Because of that, they concluded that drinking even a small amount of alcohol before bed can adversely affect sleep quality.

Also important is that the body didn’t adjust by the third night with alcohol, which led the researchers to conclude that regular nightcaps don’t cause the body to adapt over time.

Lack of REM sleep, particularly if it becomes chronic, can be a major brain health risk, since this is the stage of sleep necessary for memory consolidation and emotional processing, and it’s when you dream. If this is affected in a negative way, the researchers of the recent study suggested it might result in emotional problems, memory difficulties, and trouble focusing.

This isn’t the first time the association between alcohol and reduced REM sleep has been noted. A 2022 study published in SLEEP Advances that tracked the effects of behaviors like alcohol consumption over 36 years also found even moderate drinking could affect sleep quality.

Does this mean if you have poor sleep quality, you should quit drinking altogether? Not necessarily, but it may be a good idea to cut back or have a period of abstinence to see how your sleep improves, said Anton Bilchik, M.D., Ph.D., surgical oncologist and division chair of general surgery at Providence Saint John's Health Center in Santa Monica, California.

“There’s no doubt that alcohol increases health risks, but as with any type of behavior, it comes down to tradeoffs,” he told Runner’s World. “Everything you do should be put in context of your potential lifespan and healthspan. Most of all, it helps to pay attention to how a particular behavior, like drinking, is affecting you overall and adjust based on that insight.”