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. This begs the question: how much alcohol does it actually take to disrupt sleep? This is an area of ongoing research, but here’s what we know so far.
Why does alcohol harm sleep in the first place?
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.
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.
Clearly, alcohol doesn’t do us many favors in the sleep department—but does one glass of wine before bed really make much of a difference?
How much is too much?
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 men3) is associated with low sleep quality4, 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 time5, 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).
If you do want to enjoy a glass of wine or a bit of mezcal before bed, no shame. Just consider pairing it with habits that will help you rest up: Go to sleep at your usual bedtime, avoid late-night scrolling on your devices, and follow a relaxing sleep routine that involves a bath, a meditation session, or a sleep supplement.
Heavy drinking is associated with poor sleep quality, though we know less about how light drinking impacts sleep. All signs point to a disruption in REM sleep, though, even after a glass or two. With this in mind, on nights when you really need to catch up on zzz’s, try swapping out your nightcap for a calming sleep tea instead.