That cocktail before bedtime isn’t as helpful as you think

Having a glass of wine or other "nightcap" before bed has long been thought of as a way to help someone sleep, especially if it’s a warm drink like a hot toddy, a brandy, or mulled wine since the temperature allegedly promotes sleepiness. But a look at the evidence suggests otherwise, especially if one drink leads to more.

"There was a notion in the alcohol field that moderate drinking was good for you and had some health benefits," says Ian Colrain, president and CEO of MRI Global—a research institute based in Kansas City, Missouri—who has published research about insomnia and alcohol consumption before sleep. "Recently that guidance has changed. There are no real health benefits overall of drinking." And that’s true even when it comes to trying to combat insomnia.

The people most likely to reach for a drink before bed are often those who already struggle with falling asleep, and while it may feel like that drink helps, "it comes at the cost of worse sleep overall," Colrain says.

So how does consuming alcohol shortly before bedtime affect your sleep? National Geographic spoke to experts and examined the research to find out.

How alcohol before bedtime affects your body

Scientists still do not entirely understand why sleep is so necessary to survive, Colrain says. But clearly it is since lab animals deprived of sleep die after a month or so. And plenty of research has shown that sleep is restorative to just about every organ system in the body, including the circulatory system—alcohol can interfere with some of those restorative effects.

"Sleep is designed to give you sort of a cardiac holiday—your heart rate drops, your blood pressure drops, etc.," Colrain says. "One thing that happens with alcohol is your heart rate elevates. Certainly, if you have several drinks prior to going to bed, you will be going to bed with an elevated heart rate."

Not only does that elevated heart rate effect exist after a single drink, but it lasts well into your sleep as well, according to a study Colrain published in 2020. That study compared the effects of low, high, and no alcohol consumption from a half hour up to two hours before going to bed. Low was defined as two standard drinks for men and one for women; high was four for men and three drinks for women; and the placebo was non-alcoholic wine. Although high consumption yielded an elevated heart rate for the longest—the first six hours of sleep—even the low consumption resulted in a faster heart rate for the first four hours of sleep. "It’s really not good for your heart rate to be elevated," he says.

How drinking alcohol before bedtime affects sleep

In short, alcohol—even a small amount—makes sleep worse. In one study, women who had one or more drinks before bed, and men who had two or more, showed physiological measures that suggested a less restful sleep even with low alcohol intake.

"Of course, people metabolize alcohol differently, so it can be hard to generalize to an individual person," says David Kuhlman, a member of the board of directors at the American Academy of Sleep Medicine and a sleep physician at Bothwell Regional Health Center in Sedalia, Missouri. But there is no evidence that any amount of alcohol improves overall sleep quality.

Research has shown that alcohol interferes particularly with REM sleep—the stage when most dreams happen. Like sleep itself, scientists do not entirely understand the purpose of REM sleep except to know that it’s necessary. Just as rats deprived of all sleep eventually die, those deprived only of REM sleep die prematurely, although they last a little longer. So REM sleep is essential, even if scientists aren’t entirely sure why, Colrain says.

"What happens if you drink a lot before you go to sleep is that you might sleep a little bit more soundly—the sedative effect," but as the night goes on, your sleep becomes more disrupted, Colrain says. That includes REM sleep; the first REM cycle lasts about 10 minutes with each subsequent cycle lasting longer, up to an hour. "You’re going to be getting up to go to the bathroom, but just in general your sleep is more fragmented and less stable, so overall you end up with a worse night’s sleep even if you go to sleep maybe a little faster than you otherwise would."

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Even a small amount of alcohol can potentially disrupt the second half of your sleep, and with, say, three drinks, he said, "you're going to have disrupted sleep and feel worse the next morning than if you hadn't had anything to drink at all."

Does insomnia boost the risk of addiction?

Drinking alcohol is linked to a higher risk of sleep apnea, in general, and to more severe snoring and obstructive sleep apnea in those who already have these health problems. But one of the bigger risks is developing a dependence on alcohol. One study testing alcohol as a “sleep aid” found that two dozen adults with insomnia but no history of alcohol dependence initially slept a little longer after consuming a little alcohol before bed, but the effects wore off within a week—and the participants began increasing their alcohol intake to help them fall asleep.

"While the sedative properties of alcohol may initially help with sleep initiation, those wear off relatively quickly, requiring higher doses of alcohol over time," Kuhlman says. In short, there isn’t much good that comes of consuming alcohol before hitting the sheets. In fact, it can become a vicious cycle: a little insomnia leads to a nightcap, which leads to more drinks, which worsens sleep, which increases insomnia, which can lead to more alcohol consumption.

"Alcohol makes sleep quality and quantity worse and has the potential for causing a lifelong sleep disorder if an addiction develops," Kuhlman said. "Conversely, it is possible that treating underlying insomnia and sleep disorder may help with treating addiction issues."

What’s the relationship between alcohol dependence and sleep?

Insomnia and alcohol use disorders have long been linked, but the relationship between insomnia and alcohol dependence appears to go both ways for many people. A study in 2012, for example, found that frequent insomnia symptoms were linked to a subsequently higher risk of heavy drinking, and, in turn, heavy drinking and binge drinking were both linked to a higher risk of developing insomnia. Insomnia can also contribute to depression, a risk factor for alcohol dependence.

The sad irony is that "sleep disturbances are a clear pathway to relapse" for those who have recovered from alcohol use disorders, Colrain says. People with alcohol dependence frequently have terrible sleep that can last up to a year after they stop drinking. While insomnia can continue even after most other withdrawal symptoms, "long-term abstinence from chronic substance use can reverse some sleep problems," according to a 2016 review of the research on sleep issues and alcohol, marijuana, cocaine, and opioids.

But some don’t make it that long. "There's this perception that, well, if I have a drink, it'll help me get to sleep," Colrain says. "And then the sleep disturbance leads to them drinking, which leads to relapse." He pointed to emerging evidence that gabapentin, an anticonvulsant drug used to treat epilepsy, may help address both alcohol dependence and insomnia to avoid those relapses.

What's a better option to an alcoholic drink if you have insomnia?

According to Kuhlman, "Certainly, the best option when you are feeling like having a snack or drink before bed is to resist the urge and go to sleep." If you do decide to have something, moderation is key, he added.

Perhaps some warm milk or a hot herbal tea could help—certainly avoid anything with caffeine—but if difficulty falling asleep is a persistent problem, it’s more important to figure out what’s going on.

"The better thing is to try to get to the root cause of why you're having trouble going to sleep, and a lot of it is poor sleep hygiene," Colrain says. Sleep hygiene refers to habits that promote healthy sleep, such as keeping a consistent schedule of going to bed and waking up at the same time, having a wind-down routine before bed, avoiding bright light exposure in the hours before bedtime, not having a television or other screens in the bedroom, and using the bed only for its intended purpose. Richard Bootzin, a psychiatrist known for his role in developing effective treatments for insomnia, famously said not to do anything in the bed except "sleep and sex."

Colrain says one thing people can do is listen to the radio or a podcast with a timer that shuts off automatically after a set time, such as 20 minutes. Doing so makes you focus on something else—though avoid anything too riveting, like a true crime podcast—so you’re not focused on being unable to sleep, which would otherwise become a self-fulfilling prophecy.

Whatever you choose, reaching for the liquor cabinet isn’t likely to help and could very well hurt.