How much can you drink and still get REM sleep?

Key takeaways

• About one drink has little measurable effect on how much REM you get. Lab studies at low doses find small or inconsistent changes, though even small amounts may push your first REM period a little later.

• Around two drinks, REM starts to shrink. A 2025 analysis of 27 studies found REM sleep was delayed at about 1.5 US standard drinks and reduced at about two, for a 137 lb (62 kg) adult, and a little more for larger people.

• Your size makes a difference. The studies measure alcohol per kilogram of body weight, so a smaller person reaches those levels sooner.

• The second half of the night pays. As alcohol wears off, sleep gets lighter and more broken, even if you fell asleep faster.

• Earlier is better than later. Your body clears alcohol slowly, so drinks finished close to bedtime are still working while you sleep.

The short answer

If you want your REM sleep untouched, the honest answer is very little. About one standard drink with dinner makes little measurable difference in sleep studies. By about two drinks for a 137 lb adult, REM sleep starts later and there’s less of it, and more than that makes the effect bigger.

A 2025 meta-analysis pooled 27 controlled studies of healthy adults who drank before sleeping in a lab. On average, alcohol cut REM sleep by about 11 minutes and pushed the first REM period about 18 minutes later. The delay became significant at about 0.35 grams of alcohol per kilogram of body weight, and the loss of REM at about 0.5 g/kg. The more people drank, the more REM they lost.

What that means in drinks

A US standard drink holds 14 grams of alcohol, according to the NIAAA. That’s 12 ounces of 5% beer, 5 ounces of 12% wine, or 1.5 ounces of 40% spirits. Many real pours are bigger, and a large glass of wine or a strong craft beer can be closer to two.

Because the studies measure alcohol per kilogram, the number of drinks depends on your weight. Here’s our rough conversion of the two thresholds from the 2025 analysis.

These are averages from lab studies in which people drank within a few hours of bed. People vary, and the thresholds are where effects became measurable, not where they begin.

Women may be hit harder. In a 2011 study of 93 young adults given enough alcohol to reach a breath alcohol level of 0.11%, alcohol reduced REM across the night in both sexes, but disrupted women’s total sleep and awakenings more than men’s.

What alcohol does across the night

Alcohol changes sleep in two phases. While there’s plenty of it in your blood, it acts as a sedative. You may fall asleep faster and sleep more deeply in the first few hours, while REM is held back. A 2013 review of studies in healthy volunteers found that a later first REM period, seen at every dose, was alcohol’s most recognizable effect on REM.

Then the alcohol wears off. According to a review published by the NIAAA, at the levels typical in sleep studies, it’s cleared within about four to five hours of falling asleep, and the second half of the night brings more waking and lighter sleep. The NIAAA puts it simply. People fall asleep faster after drinking, but their sleep is fragmented and they tend to wake up earlier. If you often wake in the early hours after a night out, our post on waking up at 3am covers why.

Smaller amounts have smaller effects. In a 2006 trial, drinking to a blood alcohol level of 0.03% at bedtime had no clear effect on sleep, while 0.1%, above the 0.08% legal driving limit in most US states, dampened REM early in the night and brought lighter sleep in the second half.

Even small amounts show up somewhere

Lab sleep studies may miss subtler effects. A 2018 study of 4,098 Finnish workers compared their heart-rate readings during the first three hours of sleep on nights they drank and nights they didn’t. Even low amounts, up to about a drink for many people, reduced the body’s measured recovery during sleep, and higher amounts reduced it more. The study measured heart activity, not REM, and two of the authors worked for the company that made the heart-rate monitors.

Timing: when to stop

Your liver clears alcohol at a fairly fixed pace. The NHS says the average adult processes about one UK unit (8 grams) an hour, so a US standard drink takes nearly two hours, and people vary a lot.

Almost every study in the 2025 analysis gave alcohol within three hours of bed, so there’s little direct research on the best cutoff. But the arithmetic is straightforward. The more alcohol still in your blood when you fall asleep, the longer the night’s REM is held back and the more broken the second half becomes. Finishing earlier in the evening gives your body a head start. The same logic applies to caffeine, which we cover in how late you can drink coffee and still sleep.

Why a nightcap isn’t a sleep aid

Alcohol as a sleep aid is common. In a 1998 survey of 2,181 adults aged 18 to 45, 13% had used alcohol to help them sleep in the past year. It’s a poor tool for the job.

• The sedative effect fades. According to the NIAAA review, people build tolerance to alcohol’s sedative effects on sleep within about three nights, so a nightly drink soon stops helping you fall asleep.

• It worsens snoring and sleep apnea. A 2018 meta-analysis linked higher alcohol intake to a 25% higher risk of sleep apnea. In a 2020 analysis of 13 sleep-lab studies, alcohol increased breathing pauses by about four an hour and lowered oxygen levels.

• Less is better overall. The NIAAA’s guidance for people who drink is “the less, the better.”

If you’re relying on a drink to fall asleep most nights, it’s worth talking to a doctor about the sleep problem underneath.

How to drink and protect your sleep

• Keep it to about one drink on nights when good sleep counts.

• Drink earlier. Have it with dinner rather than right before bed.

• Know your pour. A big glass of wine or a strong beer can be two standard drinks.

• Alternate with water, and eat with it. Food slows the rise in blood alcohol.

• Expect a rougher night after a big one. Keep the next day’s plans gentle, and skip the long nap that can throw off the following night.

Frequently asked questions

Does one glass of wine affect REM sleep?

A standard 5-ounce glass, about one drink, makes little measurable difference to REM in most lab studies. A large pour can be closer to two drinks, which is where REM starts to fall for a 137 lb adult.

How long before bed should I stop drinking?

There’s no tested cutoff. Your body clears roughly one UK unit an hour, so a US standard drink takes nearly two hours. The earlier you finish, the less alcohol is in your blood when you fall asleep.

Why do I wake up at night after drinking?

As your body clears the alcohol, its sedative effect wears off and sleep becomes lighter and more broken, usually in the second half of the night. Needing the bathroom and a dry mouth add to it.

Does alcohol help you fall asleep?

It can make you fall asleep faster at higher doses, but the effect fades within a few nights of regular drinking, and the rest of the night’s sleep is worse.

Do you get extra REM sleep after you stop drinking?

Sometimes. In some studies, REM sleep increased on the nights after people stopped several nights of heavier drinking, though not every study finds this rebound.

Is beer better than wine or liquor for sleep?

No. What counts is how much alcohol you drink, not what it’s in. A standard beer, glass of wine, and shot of spirits contain about the same amount.