Sleep apnea and alcohol: how drinking affects your breathing at night

Alcohol makes sleep apnea worse. It relaxes the muscles that hold your throat open, blunts your ability to wake up and restart breathing, and in studies it raises the number of breathing pauses per hour and lowers oxygen levels. The effect is biggest in people who already snore or have sleep apnea.

The good news is that this is one of the easiest risk factors to change. Drinking less, drinking earlier in the evening and keeping up with treatment all help. This article goes through what the research shows and what it means in practice.

Does alcohol make sleep apnea worse?

Alcohol makes sleep apnea worse, and several meta-analyses agree on this. A 2018 meta-analysis pooled 14 studies with 422 people that measured breathing during sleep with and without alcohol. After drinking, AHI went up by about 2.3 events per hour on average, and mean oxygen levels during sleep went down.

The rise was much larger in people with breathing problems. In snorers, AHI went up by about 4.2 events per hour. In people already diagnosed with sleep apnea, it went up by about 7.1 events per hour. Alcohol also made each breathing event last longer and lowered the lowest oxygen level reached during the night. The authors called alcohol a modifiable risk factor that can lead to sleep apnea developing or getting worse.

A 2020 meta-analysis of 13 studies with 279 patients found a similar picture. Comparing nights with and without alcohol, AHI was about 4 events per hour higher with alcohol, and the lowest oxygen saturation was about 2.7 percentage points lower. The 2020 analysis only included studies that used in-lab sleep testing, not home tests.

If you're not sure what these numbers mean, our guide to what AHI means explains the scale.

Why does alcohol affect breathing during sleep?

Alcohol affects breathing during sleep in two main ways: it relaxes the airway and it dulls the wake-up response that ends each pause. The NHLBI says alcohol can make the muscles of the mouth and throat relax, which may close the upper airway. Sleep Education adds that alcohol can interfere with the ability to wake up from sleep and can lengthen periods of apnea.

A 1997 study showed the airway effect directly. Researchers gave men a bedtime drink of vodka in orange juice on one night and a placebo on another. Resistance to breathing in rose during sleep on both nights, but on the alcohol night the rise was more than doubled, in both snorers and non-snorers. The men breathed harder to compensate, and the authors said the combination of more resistance and more effort could make an unstable airway more likely to collapse.

The wake-up part matters because sleep apnea relies on your brain stepping in. Normally, when your airway closes and oxygen falls, your brain wakes you just enough to reopen it. When that response is dulled, pauses can last longer and oxygen can fall further, which matches the longer events and lower oxygen seen in the meta-analysis. Our article on why alcohol makes snoring worse covers the snoring side in more detail.

Can drinking alcohol cause sleep apnea?

Drinking alcohol is linked to a higher risk of having sleep apnea, not only to worse nights. A 2018 meta-analysis of 21 studies found that higher levels of alcohol consumption were associated with a 25% higher risk of sleep apnea. The result held up across different study designs and definitions.

There are caveats. The studies varied a lot, and the authors found signs of publication bias, meaning studies with positive results may have been more likely to be published. A further set of eight studies found that people with sleep apnea drank about two units a week more than those without it, but that difference wasn't statistically significant.

The NHLBI lists drinking alcohol among the lifestyle habits that raise the risk of both obstructive and central sleep apnea, alongside smoking. The NHS lists drinking alcohol among the things sleep apnoea has been linked to. Our article on sleep apnea warning signs covers the symptoms worth knowing.

Does the timing of your last drink matter?

The timing of your last drink matters because your body clears alcohol slowly. The authors of the 2018 meta-analysis noted that the body metabolizes about 7 grams of alcohol per hour, about half a standard drink. They estimated that 2 to 3 standard drinks, the amount most studies used, could take 4 to 6 hours to be fully cleared.

That means alcohol levels are highest in the first part of the night, and the authors suggested alcohol may have a bigger effect on breathing early in the night. The studies weren't consistent about this, though. One found more breathing events early in the night after alcohol, one found fewer later in the night, and one found no change.

The NIAAA says a US standard drink contains about 14 grams of pure alcohol. That's a 12-ounce can of beer at 5% alcohol, a 5-ounce glass of wine at 12%, or a 1.5-ounce shot of 40% spirits. Many real-world pours are bigger, so a "glass of wine" can easily be more than one drink.

No study has tested an exact safe cutoff time for people with sleep apnea. The NHS advice is simple: don't drink too much alcohol, especially shortly before going to sleep. Leaving several hours between your last drink and bedtime gives your body time to clear more of it.

These figures are rough estimates based on the average clearance rate cited in the 2018 meta-analysis, and individual people will differ.

What should CPAP users know about alcohol?

CPAP users should know that small studies suggest alcohol doesn't change the pressure their machine needs, so the most important thing is to keep wearing it. The 2018 meta-analysis reviewed three studies of people with sleep apnea on CPAP, with 30 people in total. In all three, alcohol did not appear to change the effective pressure needed to control breathing events.

One study did find a higher pressure was needed to control snoring in the first 2 hours of sleep after alcohol. Another suggested that the airway in people with sleep apnea is already collapsible, and alcohol didn't change that much while CPAP held it open. The authors concluded that people already on CPAP are unlikely to need a pressure change after drinking.

That's reassuring, but it comes with an important condition. The protection only works if the mask is on. It can be tempting to skip the mask after a late night, but without CPAP, alcohol's full effect on your airway returns. If your machine reports more events or more mask leaks after drinking, mention it to your sleep doctor. Our guides to getting used to CPAP and snoring with CPAP have tips for keeping it comfortable.

Does cutting back on alcohol help sleep apnea?

Cutting back on alcohol is one of the lifestyle changes doctors recommend for sleep apnea. The NHLBI lists limiting alcohol among the healthy lifestyle changes that can be very effective in treating sleep apnea, and Sleep Education says not drinking alcohol may improve sleep apnea symptoms.

We couldn't find a trial that tested cutting alcohol on its own. The closest evidence is the INTERAPNEA trial, published in 2022. It gave 89 Spanish men with moderate to severe sleep apnea and overweight or obesity either usual CPAP care or an 8-week program of nutrition changes, aerobic exercise, sleep habits, and alcohol and tobacco cessation on top of CPAP.

AHI fell by about half in the program group, and six months later 61.8% no longer needed CPAP. Weight loss probably did a lot of the work, so the trial can't tell you how much came from alcohol alone. But it shows that a package of lifestyle changes that includes cutting alcohol can make a large difference. Our guide to whether sleep apnea can go away covers the other parts.

What are practical ways to drink less before bed?

Practical ways to drink less before bed mostly come down to timing and amount, since both affect how much alcohol is still in your system when you fall asleep. Some ideas that fit what the research shows:

• Have any drink with an early dinner rather than late in the evening.
• Know your pour sizes using the NIAAA standard drink measures.
• Alternate with water or alcohol-free drinks.
• If you use CPAP, put the mask on every night, including after a drink.
• Avoid mixing alcohol with sleeping pills or other sedating medicines, which also relax the airway.

If you find it hard to cut back, that's worth raising with your doctor too. Our article on medications that can make snoring worse covers the sedative side.

When should you see a doctor?

You should see a doctor if your snoring is loud and comes with breathing pauses, choking or gasping, or if you're sleepy during the day, especially if these get worse after drinking. Those can be signs of sleep apnea, and a home sleep apnea test is often the first step.

If you already have sleep apnea and use CPAP, tell your sleep doctor if you're drinking regularly, and don't stop using your machine on drinking nights.

This article is general information, not medical advice. If you're worried about how much you drink, your doctor can help.

Read next

• Snoring vs sleep apnea
• Sleep apnea treatment options
• Sleep apnea and the heart

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.