Alcohol and sleep have a complicated relationship. On the one hand, we have an entire category of cocktails (nightcaps) that are supposed to lull us into slumber. And alcohol can bring on sleep more quickly. But anyone who’s ever had a frustratingly restless night after drinking might wonder whether alcohol is really to blame for their sleep problems.
Indeed, though alcohol can cause people to fall asleep more quickly, it does not offer a quality night’s sleep, and often leads to overnight awakenings.
“It’s a catch-22,” says Julia Kogan, a health psychologist who focuses on behavioral sleep medicine at the Department of Veterans Affairs. “Alcohol has a drowsy impact that helps people fall asleep, but you don’t get the quality and quantity of sleep you need to feel rested.”
Scientists have been studying the relationship between alcohol and sleep since the 1930s. The research has found that drinking impacts every stage of sleep, leading to tossing, turning, and sometimes hangovers the next day. Read on to understand the physiological impact of alcohol on your body, and alcohol’s effect on sleep.
How does alcohol affect sleep?
To understand how alcohol affects sleep, it helps to know exactly what the body does once you’ve started to drink. As alcohol is digested, it’s absorbed into the bloodstream and carried into every organ. The body circulates blood in just 90 seconds, so you start to feel the effects of alcohol fairly quickly (cue the drowsiness!). Your blood alcohol concentration (BAC) starts to rise, but just how quickly that happens depends on many things, like whether you’ve had a big meal, how much you’ve had to drink, and certain genetic factors.
Like other toxins the body needs to neutralize, alcohol is sent primarily to the liver to be metabolized (although some of it is processed in other organs and tissues as well). The liver produces alcohol dehydrogenase (ADH), and enzyme that converts the alcohol into acetaldehyde, then acetate, and finally two substances the body can easily dispose of: carbon dioxide and water.
The body takes about four to five hours to get rid of half the alcohol you consume. That means it can take around 25 hours before all of it is cleared from your system. In the meantime, it continues to affect lots of organs and processes in the body, including your sleep.
“A large part of alcohol enters the brain by crossing through the blood-brain barrier, which can increase the release of gamma-aminobutyric acid (GABA),” says Allison Brager, Ph.D., a neurobiologist with expertise in sleep and circadian rhythms and a National Academy of Sports Medicine (NASM) certified wellness coach.
This neurotransmitter blocks certain signals in the central nervous system and produces a calming effect, which is why it feels easier to fall asleep after drinking. With that said, the sleep-promoting benefits of alcohol generally diminish after you’ve consumed alcohol before bed for several days in a row, so this is far from a reliable technique to drift off.
Why alcohol can wake you up overnight
Alcohol increases the level of the stress hormone epinephrine in your body a few hours after your last drink, leading to an increase in your heart rate.
“In the middle of the night, when the liver is metabolizing that alcohol, people usually wake up and have an inability to fall back asleep,” says Brager. “Consuming alcohol suppresses the central nervous system, and when it’s been suppressed for a significant period of time, the reverse happens. The body gets excited after it’s been artificially suppressed through the alcohol.” Besides fitful sleep, you might need to get up to go pee a few times (alcohol is a diuretic, after all!). Alcohol relaxes your muscles and restricts your airflow, so you might find yourself snoring.
Does alcohol make you sleepy?
If you’ve ever had a couple of drinks, you don’t need a scientist to tell you that alcohol can make you feel sleepy. This drowsiness occurs because alcohol causes a release of GABA in the brain, which slows down brain activity and makes you feel tired.
Just because alcohol has a sedative effect doesn’t mean you’ll get better sleep, though. Research has shown that drinking messes with sleep cycles and leads to frequent awakenings in the night and early morning.
Overall, your sleep is likely to be shorter, lighter, and more interrupted when you have alcohol in your system.
How alcohol affects each stage of sleep
The first stage of sleep is the lightest. It’s that transition period from wakefulness to sleep that generally only lasts a few minutes. Alcohol has been shown to increase stage 1 sleep during the second half of the night, especially for those who’ve been drinking heavily.
Sleep gets a little deeper when you reach stage 2. During this stage, your eyes stop moving and your body temperature drops to prepare you for deeper sleep. Stage 2 sleep typically takes about 25 minutes the first time you enter it during the night, and as your sleep cycle repeats itself, this stage gets longer and longer, eventually making up about 45% of your total sleep. However, this can look different after you’ve been drinking. Alcohol has been shown to consolidate the first half of your sleep and lead to more disruptions in the latter half of the night, which can change how much time you ultimately spend in this stage.
Stage 3, also called slow-wave sleep, is the deepest stage, typically making up about a quarter of your sleep during the night. This is the phase when the body performs essential maintenance, like repairing tissue, strengthening the immune system, and developing bones and muscles. Alcohol has been shown to boost the amount of slow-wave sleep you get in the first half of the night, which could potentially increase the risk of sleepwalking, sleep apnea, and other sleep problems. The sleep disruptions that tend to occur in the second half of the night after you’ve been drinking could make it difficult to enter and maintain stage 3 sleep, so you’re unlikely to feel refreshed in the morning.
Rapid-eye movement (REM) sleep usually happens about 90 minutes after you fall asleep. This is the dream phase, when your eyes shift rapidly from side to side as you snooze. During REM, your breathing, heart rate, and blood pressure almost look the same as when you’re awake. For those who’ve consumed sufficient alcohol, REM sleep in the first half of the night could be impacted significantly. Otherwise, moderate to heavy alcohol consumption typically reduces the REM stage in the second half of your sleep, which could have an impact on your concentration, memory, and motor skills.
Can alcohol help sleep?
Even though drinking can help you fall asleep quickly, alcohol doesn’t help sleep over the course of the night. Sleep problems associated with alcohol include:
- Frequent awakenings
- Disrupted sleep architecture
- Worsened sleep apnea
- More severe snoring
- Lower-quality sleep
- Less sleep overall
- An increase in daytime sleepiness
Alcohol and insomnia
Alcohol and insomnia often exist in a vicious cycle. People who struggle to get to sleep and stay asleep may turn to alcohol to help induce that much-needed slumber, explains Brager.
“They’re not getting restorative sleep because they drink too much, but they keep drinking to self-medicate to try to deal with the insomnia,” she explains. “It’s a self-perpetuating problem.”
Insomnia is very common among people with alcohol use disorder. A research review from the U.S. Department of Veterans Affairs estimates that between 36% and 91% of people with alcohol dependence experience insomnia. The research also showed that sleep problems often occur before a person develops issues with alcohol, but alcohol dependence may also lead to insomnia, creating a complicated cycle.
Tempting as it might be to mix up a nightcap when you’re dealing with chronic sleep troubles, alcohol is unquestionably not a treatment for insomnia. In fact, it’s only likely to make your sleep problems worse. For something more likely to work, Kogan recommends cognitive behavioral therapy for insomnia (CBT-I).
“It’s the gold-standard treatment for insomnia. It’s usually six to 10 sessions, and no medications are required. People often see great results from it,” she says.
Alcohol and sleep apnea
Like alcohol and insomnia, drinking is closely connected with sleep apnea. Research has found that people who consume any alcohol have a 25% higher risk of developing obstructive sleep apnea (OSA). Drinking is also linked with the lowest oxygen saturation levels among people with OSA, as well as anyone prone to snoring, according to a 2020 systematic review. That same review found that people experienced an average of one to two more “apneic events” (or involuntary breathing pauses) every hour after drinking.
So why does alcohol have such a negative impact on sleep apnea? It all goes back to the ways your body responds to alcohol as a sedative, says Kogan.
“With sleep apnea, the airway starts to close when you’re sleeping, and drinking alcohol relaxes the throat muscles even more,” explains Kogan. “This can make breathing worse and lead to even heavier snoring. It’s definitely not a good thing for people with sleep apnea.”
Alcohol and sleep FAQ
Why does alcohol wake you up in the middle of the night?
Since alcohol impacts many systems in your body, there are several reasons why alcohol can wake you up in the middle of the night. You might wake up due to things we’ve already covered, such as needing to pee, experiencing sleep apnea, or snoring heavily. Many cocktails and wines also contain high amounts of sugar, which can stimulate your body as you start to metabolize the drinks. But alcohol also suppresses the production of glutamine, a type of amino acid and a natural stimulant. As your body metabolizes the alcohol, glutamine production kicks into overdrive and wakes you up. It’s one part of the rebound effect the body goes through as it clears alcohol from your system, which is linked with frequent sleep disturbances in the second half of the night.
How long before bed should you stop drinking?
Stop drinking at least three hours before bedtime, says Kogan.
“The further from sleep you stop drinking, the better,” she says. “If you’re following the recommended daily guidelines of alcohol use (no more than two drinks for men, one drink for women), three hours should give the body enough time to start to metabolize the alcohol.”
When Brager conducted research on how the timing of alcohol consumption affected sleep, she found that daytime drinking was associated with the least amount of sleep disruption.
Does wine help you sleep?
Wine is just like any other type of alcohol when it comes to your sleep. It can initially make you drowsy and help you fall asleep more easily. But over the course of the night, it can wreak havoc on your sleep architecture and lead you to toss and turn. Rather than sipping red wine, consider instead having a glass of tart cherry juice, which is a good natural source of melatonin.
Is it OK to take sleeping pills and drink alcohol?
Steer clear of alcohol when you take sleeping pills. Drinking even just a small amount of alcohol around the time you take sleeping medication could put you at risk of unpleasant side effects, like dizziness, confusion, or feeling faint. The combination of alcohol and sleeping pills can even cause your breathing rate to drop to a dangerously low level and make you unresponsive. Only take your sleeping medication as directed by a doctor or the label.