Alcohol and sleep: falling asleep faster isn't resting better

Falling asleep sooner: less clear than it seems

Alcohol enhances the action of GABA, a substance that dampens the activity of neurons; this is one of the proposed explanations for its sedative effect.³ But when sleep is measured in a laboratory, the effect on how long it takes to fall asleep is smaller than people usually think.

A 2013 review, which went over the studies without combining their results into a single figure, reported that alcohol shortened that time at any dose.² The 2025 meta-analysis did combine them: 27 studies with healthy adults aged 18 to 70, almost all with the alcohol drunk in the three hours before bed. On average, the difference was 2 minutes and couldn't be told apart from chance; the shortening was only clear at high doses, of about 0.85 g of alcohol per kilogram of body weight.¹ For a person weighing 62 kg, the reference weight in that study, that's about 53 g of alcohol: about five standard drinks.

In Spain, a standard drink (known as a UBE) contains 10 g of alcohol: roughly a 100 ml glass of 13% wine, a 250 ml glass of 5% beer, or 30 ml of a 40% spirit.⁸ It's the same measure the meta-analysis uses.¹

There's a likely reason for such a small effect: in more than eight out of ten measurements without alcohol, people were already falling asleep in under 20 minutes, so there was little room to shorten it. The authors suggest that the effect could be larger in people who take a long time to fall asleep. Perception also plays a part: in three of the five studies that asked, people believed they fell asleep sooner with alcohol, and in one of them they believed it even though the objective measure didn't change.¹

What changes in the first and second halves of the night

Sleep moves through cycles of 90 to 120 minutes. In the first ones, deep sleep predominates and REM periods are short; in the last ones, REM takes up much more time and deep sleep almost disappears.³ That's why it matters at what point in the night alcohol is acting, and at what point it's already gone.

Of all the changes in REM, the delay of the first REM period is the one the 2013 review considers the most recognizable.² The 2025 meta-analysis put a number on it: on average, the first REM period was delayed by 18 minutes, and REM over the whole night was reduced by 11 minutes.¹

For years it was thought that this lost REM was made up at the end of the night, with a “rebound” once the alcohol had been cleared, so that the total didn't change.³ When the studies were combined, REM over the whole night was still lower.¹

How much alcohol it takes for it to show

The meta-analysis estimated the dose at which each change could be told apart from chance. The order is what's interesting: REM is disrupted by much less alcohol than it takes to fall asleep sooner.¹

The effect grows with the amount: according to the model, each gram of alcohol per kilogram of body weight took about 40 minutes of REM off the night.¹ A heavier person needs more grams for the same dose per kilogram, and other factors, such as eating while drinking, change how quickly blood alcohol rises.¹

What if you drink earlier? Almost all the studies gave the alcohol in the three hours before bed, so it isn't known how much time in between is enough. In one of them, a low dose taken six hours before sleep increased time awake during the night, even though no alcohol could be detected on the breath at bedtime.¹

What shows up in your heart rate while you sleep

A study of 4,098 Finnish employees who wore a chest sensor for several days compared each person's first three hours of sleep on nights with and without alcohol. With more alcohol, heart rate was higher and heart rate variability (RMSSD) lower. The change already showed up in the group that drank least, where on nine out of ten of those days the intake was a single 12 g drink.⁵

A 2026 study of 20,968 users of a commercial wristband, which measures heart rate with light, found the same pattern when comparing each person with themselves: drinking more than usual was associated with a higher nighttime heart rate, lower variability and slightly less sleep time. On nights when the last drink came earlier than usual, the changes in heart rate and variability were somewhat smaller.⁶

What the variability your watch shows means, and why it shouldn't be compared with anyone else's, is covered in the article on heart rate variability; what a device can estimate about your sleep stages, including REM, in what watches and rings can tell you about your sleep.

Why it doesn't work as a sleep aid

In multi-night studies with healthy people, alcohol's sedative effect and the changes it caused in sleep stages faded within about three nights. The authors of a review on alcohol and sleep warn that this tolerance can lead people to drink more and more in order to sleep.³

This matters above all for people who sleep badly. According to US data cited in the 2001 review, 30% of people with persistent insomnia had used alcohol to sleep in the past year.³ In an experiment with 11 people with insomnia and 9 without, a dose of 0.5 g/kg deepened sleep in the first half of the night in those with insomnia, but reduced REM over the whole night in both groups. And when they could choose a drink before bed, the people with insomnia chose the one containing alcohol on 67% of nights, compared with 22% for those who slept well.⁴

Sleeping worse also shows the next day: in a study cited in the same review, after drinking before bed people were slightly less alert and performed worse on divided-attention tasks. The changes were small, but they can matter in demanding tasks such as driving.³

And there's a reason that goes beyond sleep: Spain's Ministerio de Sanidad points out that there is no safe limit for drinking alcohol, that any drinking carries a risk and that the less, the better.⁷ That's why it speaks of “low-risk” drinking, not safe drinking.⁸

If you want to see how it affects you

The figures from the studies are group averages. If you want to know what happens to you, for a few weeks write down the nights with and without alcohol, how much and at what time, and how you slept and how you felt when you got up; if you wear a watch, look at your trend rather than one night's number. We explain how to set up a test like this without fooling yourself in how to turn a wellness data point into a question and a test.

Change only one thing at a time. If you also drink coffee in the afternoon, keep in mind that caffeine has its own timing, as we explain in the article on caffeine and sleep. And if what you want is for alcohol not to affect your night, the most direct way is not to drink that night: how much time in between is enough hasn't been established.¹

When it's worth asking for help

It's worth talking to a professional at your primary care center if drinking has become your usual way of getting to sleep, if you notice you need more to get the same effect, or if you find it hard to cut down even though you want to. This is general guidance, not a way to assess your drinking: that assessment is up to that professional.

If you take medications, Spain's Ministerio de Sanidad recommends not drinking alcohol when the medication interacts with it;⁹ ask at your primary care center or at the pharmacy whether that applies to you. Its healthy lifestyles website (in Spanish) brings together advice for cutting down and a locator for addiction treatment centers.

And if what worries you is that you've been sleeping badly for a while, whether or not it has to do with alcohol, read when habits aren't enough.