How Much Alcohol Does It Take To Disrupt Your Sleep? Unpacking The Research

Waking up after a bout of heavy drinking is far from a pleasant experience. But for many people, having one or two drinks before bed doesn't necessarily lead to the same headaches, grogginess, or fatigue as a full-on night out.

Although booze might help you fall asleep faster in some cases, it seems to have a net negative effect on sleep quality. Due to how it affects the neurotransmitters gamma-aminobutyric acid (GABA) and glutamate, alcohol disrupts our natural sleep architecture—particularly during the second half of the night.

"As alcohol metabolizes through your body, it can suppress REM sleep, rapid-eye-movement sleep, which is the part of sleep where dreams mostly occur," Wendy M. Troxel, Ph.D., a clinical psychologist and certified behavioral sleep medicine specialist, previously explained to mindbodygreen.

During REM sleep—which usually starts 90 to 120 minutes after falling asleep—we form and consolidate memories1, sharpen motor skills, and process emotions. We spend more time in REM sleep during the second half of the night, when the effects of pre-bed alcohol seem to be at their strongest. By suppressing this all-important stage, alcohol can spur fatigue, brain fog, and emotional dysregulation.

To add insult to injury, alcohol is also a diuretic, so it can cause us to wake up in the middle of the night to go to the bathroom—further compromising deeper sleep stages like REM. It may also contribute to nagging heartburn in some people, or be flavored with sugars that disrupt rest too.

The topic of alcohol and sleep is of special interest to researchers lately, with nearly 600 studies2 published on it so far this year. However, the vast majority of this research is on people who are heavy drinkers or have alcohol use disorder.

There's no doubt that excessive alcohol use (which the CDC defines as 4+ drinks for women and 5+ drinks for men) is associated with low sleep quality3, and the impact seems to be dose-dependent. That is, the more you drink before bed, the worse your sleep will be.

That said, less research has focused on how low to moderate drinking—1-2 drinks per night, for example—impacts sleep. We still have more to learn on this topic, but it does seem that any amount of alcohol can throw off sleep architecture.

According to a review study in Alcoholism: Clinical & Experimental Research, alcohol (at all doses) delays the first REM sleep period and reduces total night REM sleep. "One consequence of a delayed onset of the first REM sleep would be less restful sleep," corresponding author Irshaad Ebrahim, MD, said in a statement.

As for whether certain types of alcohols are less disruptive to sleep, or if repeated light drinking impacts sleep quality over time4, we don't have any good answers and it likely depends on the person.

While everyone metabolizes alcohol a bit differently, the best way to ensure that booze doesn't harm your sleep is to avoid it entirely or drink it earlier in the day—at least 4-6 hours before bedtime. Switching over to low- or no-ABV options closer to bedtime may also help keep REM sleep intact (just watch out for added sugars).