Alcohol and sleep apnea: what drinking does to your breathing at night

Alcohol makes obstructive sleep apnea worse. It relaxes the muscles that hold your throat open and dulls the brain's alarm that wakes you to breathe, so pauses come more often, last longer and drop your oxygen lower. In controlled studies the effect was small in people who don't snore and much bigger in people who already snore or have sleep apnea. Over the long run, people who drink more are also more likely to have sleep apnea in the first place.

Below: how alcohol affects the airway, what the studies measured, how many drinks and how late matter, the signs to look for, a self-check, what to tell your doctor before a sleep test, and a 2-week way to see what cutting back does for your own nights.

What sleep apnea is, in short

In obstructive sleep apnea (OSA), the soft tissue at the back of the throat collapses during sleep and blocks air, partly (a hypopnea) or fully (an apnea), for 10 seconds or more. Your oxygen drops, your brain half-wakes you to reopen the airway, and you fall back asleep, often without remembering. This can happen dozens of times an hour.

Doctors count these events per hour of sleep, the apnea-hypopnea index (AHI). The usual grades for adults are:

The Sleep Foundation, citing clinical reviews, puts OSA at 10% to 30% of US adults, and many don't know they have it. Central sleep apnea is a different, less common kind, where the brain briefly stops sending the signal to breathe.

How alcohol makes sleep apnea worse

• It relaxes the throat. Alcohol lowers the tone of the muscles that hold the airway open, including the tongue. A floppier airway collapses more easily, especially lying on your back.
• It slows the wake-up alarm. Normally a drop in oxygen or a rise in carbon dioxide wakes you enough to reopen the airway. Alcohol dulls that response, so each pause can last longer before you breathe again.
• It hits the first half of the night hardest. That's when the alcohol level in your blood is highest. As it wears off, sleep becomes lighter and more broken for other reasons (see alcohol and sleep quality).
• It makes snoring louder. The same relaxed tissue vibrates more. People who never snore often snore after drinking.
• It adds up with sedatives. Sleeping pills, benzodiazepines, opioid pain medicine and some antihistamines also relax the airway and slow breathing. Together with alcohol, the effect can be dangerous.

What the studies measured

Two reviews give the clearest numbers.

Alcohol on the night itself. Kolla and colleagues (Sleep Medicine Reviews, 2018) pooled 14 studies with 422 people who slept in a lab after drinking and after not drinking. After alcohol:

The lowest oxygen level of the night was also lower after alcohol, and breathing events lasted longer. In plain words: a drink barely matters for someone with an open airway, but for someone with sleep apnea it can add enough events to move them up a grade on some nights.

Drinking over the years. Simou, Britton and Leonardi-Bee (Sleep Medicine, 2018) reviewed 21 studies and found that people who drank more had about a 25% higher risk of sleep apnea than people who drank little or none. That kind of study shows a link, not that alcohol alone caused it; drinking also goes with weight gain and poorer sleep, which add their own risk.

How much and how late matters

The studies mostly gave people the equivalent of a few drinks within hours of bed. The pattern that matters for your night:

• More drinks, more effect. The Sleep Foundation notes that negative effects on OSA are seen at two to three standard drinks, and most sleep disruption with three or more before sleep.
• Closer to bed, more effect. The liver clears about one standard drink an hour. Two glasses at 6 p.m. are mostly gone by 9 or 10; two at 10 p.m. are still in your blood when your airway is most relaxed. The Sleep Foundation's advice is to stop at least 4 hours before bed.
• Bigger pours count as more than one. A 9 oz glass of 13% wine is close to two standard drinks. Our standard drinks in a bottle of wine guide shows how to count yours.

Signs you might have sleep apnea

• Loud snoring most nights, not only after drinking.
• Someone has seen you stop breathing, choke or gasp in your sleep.
• Waking with a dry mouth, a sore throat or a headache.
• Feeling sleepy in the day even after a full night in bed; nodding off reading, watching TV or driving.
• Waking often to use the bathroom at night.
• High blood pressure, especially if it's hard to bring down.
• Poor focus, irritability or low mood in the day.

Many of these also show up after an evening of drinking without any apnea at all. The useful question is whether they happen on dry nights too.

A quick self-check: STOP-BANG

Doctors often screen with a short questionnaire called STOP-BANG. One point for each yes:

A score of 0 to 2 means a lower chance of moderate or severe OSA; 3 or more means a higher chance and is worth raising with a doctor. It's a screen, not a diagnosis: only a sleep test tells you for sure. Women's risk rises after menopause, so a low score doesn't rule it out for a tired, snoring woman over 50.

Drinking and the sleep test

Sleep apnea is diagnosed with a sleep study: a home sleep apnea test (a small device worn overnight in your own bed) or a night in a sleep lab. If you drink most evenings:

• Follow your sleep center's instructions about alcohol, caffeine and medicines on the test day. Ask if they don't say.
• Tell them how much and when you usually drink. A test on a dry night can look milder than your usual nights; a test after drinks can look worse. Either way, your doctor reads the result better knowing your pattern.
• Don't mix alcohol with any sleep aid you've been given for the test.

If you have sleep apnea: can you still drink?

That's a question for your own doctor, who knows your AHI and your oxygen levels. Many sleep doctors advise people with OSA to avoid alcohol in the evening, or at least close to bed. If you do drink:

• Keep it early, with food, and stop at least 4 hours before bed.
• Keep it to one or two standard drinks, not three or more.
• Always use your CPAP or oral device, especially on nights you drank. The Sleep Foundation reports that a few small studies suggest CPAP at the usual pressure can prevent most of alcohol's extra breathing events, but the evidence is limited.
• Don't drive drowsy. Untreated sleep apnea and alcohol both slow reaction time.

Can cutting back on alcohol help sleep apnea?

It can make the nights you'd have drunk look more like your dry nights: fewer events, less snoring, better oxygen. It won't cure apnea caused by the shape of your airway, your weight or your age. What tends to help most, together:

1. Fewer evening drinks, earlier. The quickest change you control.
2. Weight. Extra weight around the neck is the biggest risk factor for OSA in adults. Drinks add calories and late snacks; see will drinking less help me lose weight?
3. Side sleeping. Many people's apnea is worse on their back.
4. Treatment. CPAP, an oral appliance from a dentist trained in sleep, or other options your doctor offers.
5. Fixing nasal blockage. Allergies or a blocked nose make mouth-breathing and snoring worse.

For what else changes in the body when you cut back, see the benefits of drinking less alcohol and what happens when you stop drinking for a week.

A 2-week test you can run at home

This doesn't diagnose anything. It shows you, and your doctor, how much your drinking changes your nights.

If week 2 is clearly better, alcohol was adding to your nights. If you still snore loudly, wake gasping or feel sleepy all day in week 2, take the log to your doctor: those signs on dry nights point to sleep apnea that needs testing. Either way, the log makes the appointment more useful.

When to see a doctor

• Someone has seen you stop breathing or gasp in your sleep.
• You're sleepy in the day, or have nodded off while driving.
• You score 3 or more on STOP-BANG.
• You have high blood pressure, heart rhythm problems or have had a stroke and snore.
• You take sleeping pills or opioid pain medicine and drink in the evening.
• You drink heavily every day and want to stop. Stopping suddenly can bring withdrawal; a doctor can help you do it safely. The free, confidential SAMHSA National Helpline is open every day at 1-800-662-4357.

Questions people ask

Can alcohol cause sleep apnea?

It can bring on apnea events in people whose airway is already narrow, and long-term heavier drinking is linked with a higher risk of having sleep apnea. Whether alcohol alone causes it is less clear, because drinking also goes with weight gain and other risk factors.

How long after drinking does sleep apnea get worse?

The effect is strongest while alcohol is in your blood, which for most evening drinkers is the first half of the night. That's why stopping at least 4 hours before bed helps.

Does one drink affect sleep apnea?

For most people the effect of one drink with an early dinner is small. In the lab studies the effect grew with the dose and was largest in people with diagnosed OSA, so if you have it, ask your doctor what's safe for you.

Can I use my CPAP after drinking?

Yes, and you should. Skipping CPAP on drinking nights is when you need it most. Don't drink to the point where you can't put it on properly.

Will stopping drinking cure my sleep apnea?

Usually not on its own. It can reduce the extra events alcohol adds and help with weight, but most people with moderate or severe OSA still need treatment.

Why do I snore only when I drink?

Alcohol relaxes the soft tissue in your throat, so it vibrates more as you breathe. Snoring only after drinking is common; snoring every night, with pauses or gasping, is worth checking.

More on drinking less: all our drink-less guides.

Sources: Kolla BP, Foroughi M, Saeidifard F, Chakravorty S, Wang Z, Mansukhani MP, "The impact of alcohol on breathing parameters during sleep: a systematic review and meta-analysis", Sleep Medicine Reviews, 2018. Simou E, Britton J, Leonardi-Bee J, "Alcohol and the risk of sleep apnoea: a systematic review and meta-analysis", Sleep Medicine, 2018. Sleep Foundation, "Alcohol and Sleep Apnea". American Academy of Sleep Medicine, apnea-hypopnea index severity grades for adults. Chung F et al., "STOP-Bang Questionnaire: a practical approach to screen for obstructive sleep apnea", Chest, 2016. SAMHSA National Helpline, 1-800-662-4357.