Sleep apnea quadruples the risk of dying early, and most people who have it do not know

In two cohorts followed for 18 and 20 years, people with moderate to severe sleep apnea died at roughly four times the rate of people without it. In the same population, 93% of women and 82% of men who had it had never been diagnosed. Here is what the numbers actually support, and how to check your own nights.

Of all the things that can be quietly wrong with you while you feel only vaguely unwell, sleep apnea has the worst ratio of consequence to diagnosis. The breathing stops, dozens or hundreds of times a night, each pause pulling you out of deep sleep without waking you enough to remember it. In the morning you know only that you are tired again.

The number

Two long-running cohorts followed people who had been measured with full overnight sleep studies, then waited to see who died.

The Wisconsin Sleep Cohort tracked 1,522 people for 18 years (Young 2008). Adjusting for age, sex, BMI and other factors, people with severe sleep-disordered breathing died at 3.0 times the rate of people with none (95% CI 1.4-6.3). When the researchers removed everyone who had used CPAP, so that the comparison was untreated apnea against none, it rose to 3.8 times (1.6-9.0). Cardiovascular death alone came out at 5.2 times, on a wide confidence interval.

The Busselton Health Study in Western Australia followed 397 residents for 20 years (Marshall 2014). Moderate to severe apnea carried 4.2 times the all-cause mortality (1.9-9.2), along with 3.7 times the stroke risk and 2.5 times the risk of developing cancer.

So the fourfold figure is real, and it is not one study. Two things to hold onto, though, because they change who it applies to.

It is about severe apnea, not any apnea. Severity is counted as events per hour of sleep: 5 to 15 is mild, 15 to 30 moderate, above 30 severe. The mortality signal lives at the top of that scale. In Busselton, mild apnea was actually associated with halved mortality, which is almost certainly noise in a small sample rather than a benefit, but it tells you how little the bottom of the range resembles the top.

Both studies are observational. People with severe apnea differ from people without it in ways no statistical adjustment fully removes. The honest reading is that severe untreated apnea marks a substantially higher risk of dying early, not that every event is a measured subtraction from your life.

Almost nobody who has it knows

This is the part that makes the number actionable. In a sample of 4,925 working adults with no particular barrier to healthcare, researchers compared who had been diagnosed with who turned out to have it on an overnight study. 93% of the women and 82% of the men with moderate to severe sleep apnea had never been diagnosed (Young 1997).

The scale is not small either. A 2019 analysis put 936 million adults aged 30 to 69 worldwide with mild to severe obstructive sleep apnea, and 425 million in the moderate to severe range (Benjafield 2019). Most of them do not know.

Undiagnosed is the normal state for this condition. If you have it, the single most likely reason nobody has told you is that nobody has looked.

Why a mental health app cares

Because untreated apnea produces a symptom list that is nearly word for word the symptom list for depression: exhausted on waking, flat, irritable, unable to concentrate, no drive, no interest. Someone who feels all of that and sleeps next to nobody has no way to know their breathing stopped two hundred times.

The association is not just overlap. The Wisconsin researchers also followed the same population for depression over repeated four-year intervals (Peppard 2006). Each step up in apnea severity raised the adjusted odds of developing depression by 1.8 times, and people with moderate or worse apnea had 2.6 times the odds compared with people with none. It was a dose-response relationship, and the apnea was measured before the depression appeared.

This is the same argument Mura makes about anemia, thyroid function and B12. Nobody is claiming that low mood is usually a breathing problem. The claim is narrower and more useful: a handful of physical conditions imitate depression closely enough to be worth ruling out, they are all testable, and a therapy session cannot find any of them.

What treating it does, and what is not yet shown

Be careful here, because this is where the story usually gets oversold.

The largest trial of CPAP for preventing cardiovascular events, SAVE, randomized 2,717 people with moderate to severe apnea and existing heart or cerebrovascular disease, and followed them for 3.7 years (McEvoy 2016). It did not work. Events occurred in 17.0% of the CPAP group against 15.4% of usual care, a hazard ratio of 1.10. Average use was 3.3 hours a night, which is a large part of the explanation and also what real-world adherence looks like.

What the same trial did show: CPAP significantly reduced snoring and daytime sleepiness, and improved mood and quality of life. Those are the outcomes that matter most to someone who is tired and flat all the time, and they are the ones Mura is interested in.

So: finding apnea is clearly worth doing, and treating it reliably improves how you feel. Whether treating it buys back the fourfold mortality figure is not established, and anyone who tells you it is has gone past the evidence.

The signs worth taking seriously

Someone has seen you stop breathing, or heard you gasp or choke in your sleep

Loud snoring, most nights, loud enough to be a problem for someone else

Waking unrefreshed no matter how long you were in bed

Falling asleep in the day when you did not intend to

Morning headaches, a dry mouth on waking, getting up repeatedly to urinate

High blood pressure that does not respond well to treatment

Two caveats. You can have apnea without snoring, which is more common in women and part of why the underdiagnosis figure is so skewed. And snoring on its own, with none of the rest, is usually just snoring.

Recording your own night

Mura has a tool for exactly this. You put the phone on the nightstand, start it, and it records through the night using the microphone only, for up to 11 hours. In the morning it reports breathing pauses of 10 seconds or longer, whether a pause was followed by a gasp, how much of the night you spent snoring, your estimated respiratory rate, and a pauses-per-hour figure banded the same way clinicians band severity: under 5, 5 to 15, and 15 or more.

What it is honestly not: a diagnosis. It hears your breathing, so it cannot measure what your blood oxygen did when the breathing stopped, and oxygen desaturation is half of what a real sleep study scores. It cannot produce an apnea-hypopnea index, and anything that claims to from audio alone is overstating itself. A quiet room, a partner who snores, or a phone under a pillow all degrade it.

What it is good for is the thing that is otherwise impossible: turning "I think I sleep badly" into something specific enough to take to a doctor. "I recorded six nights and averaged 22 pauses an hour, most of them followed by a gasp" starts a different conversation than "I am always tired." It is free, there is no waiting list, and you find out in the morning.

The test that settles it

If the signs are there, or your own recording keeps flagging pauses, the next step is a doctor and a real sleep study. That is either a home sleep apnea test, a kit you wear for a night that measures airflow, effort and blood oxygen, or full polysomnography in a lab. Both produce the number that treatment decisions are actually made on. Mura's recording is a reason to ask for one, not a substitute for it.

The short version

Severe untreated sleep apnea carries roughly three to four times the risk of dying early, more than four in five cases are undiagnosed, and it imitates depression well enough that people spend years treating the mood and never looking at the breathing. The condition is common, the test is routine, and the only unusual thing about it is how rarely anyone checks.

General information only, not a diagnosis. If you are being treated for anything, keep doing it and raise this with your clinician.

This article is for general information and is not a substitute for professional care. If you are in crisis or thinking about harming yourself, please contact your local emergency services or a crisis line. See crisis lines.