Sleep apnea and pain: not the clear link you’d think

It seems a little fishy to me that practically everyone who gets tested for obstructive sleep apnea ends up with a CPAP machine prescription. It reminds me of the way everyone who ever steps on a foot scanner gets a diagnosis and sales pitch for orthotics. Or how you can’t walk by a dentist on the street without getting an unsolicited mouth guard prescription. Are CPAP machines a case of profit-powered pathologization and overdiagnosis?

I don’t know — and the question is out of my lane. But I wonder! And it has been on my mind since spending two nights in a sleep lab recently:

Sleep-lab selfie! Hooked up to be measured all the ways, all night long. I applied a “night-vision” filter just for kicks.

Most sleep studies are pretty basic, focused on detecting common sleep disorders like sleep apnea. You can even get a “no-cost home sleep apnea test” now. (Does that really work? Oops, back to my lane …)

And then there’s the UBC Sleep Clinic — a hardcore, high-tech sleep lab that checks for everything. “This is the coolest lab I’ve worked in,” my technician said (of seven). And then he really hooked me up. They test for many sleep disorders, and that was the whole point for me, a champion insomniac with weird sleep problems since I was a toddler.

So I spent two nights in that lab, swaddled in medical tape, a sarcophagus of wires, electrodes, and about a pound of waxy adhesive in my hair. This was two weeks ago and I’m still finding scraps of glue residue. I had a mic taped to my throat, two different nostril sensors, motion detectors on my legs. A mighty electric ponytail of bundled leads snaked from the back of my head to a hub on the wall, which passed data to a room full of computers that looked like a small version of NASA’s Mission Control. Then came several minutes of astronaut-style pre-flight checks, including a request to “please make snoring sounds.”

It was not a restful experience.

I have my suspicions about what’s wrong with my sleep, and it ain’t apnea, but I will let the doctor reach his own conclusions (still pending). But if I did have sleep apnea, would it explain something about my own long-term chronic pain? Now that question is in my lane …

Do people with sleep apnea get more chronic pain?

Sleep deprivation probably does intensify pain, and apnea is synonymous with lousy sleep, so … surely this is a no-brainer? But the science is surprisingly wishy-washy.

In 2018, Charokopos et al. found the studies split — the experimental-pain studies even disagreed on direction — and hardly any good evidence that treating apnea with CPAP reduces pain. That didn’t stop them from concluding, “Overall, there is an association.” Maybe, but it’s hardly the slam dunk I expected.

In another 2018 review, Mathias et al. reported that people with chronic pain sleep worse in the lab than healthy people. Imagine my surprise! Sleep labs are rough on anyone, but especially if you hurt: try shifting off a sore hip while wearing a wire-sarcophagus. But the apnea signals were only modestly worse. More of a hint of a correlation than a confirmation.

And a link isn’t a cause, of course. Maybe people with chronic pain suffer more from sleep apnea — their sleep might be unusually shallow to begin with, thanks to the pain, making the apnea feel worse and diagnosis likelier. Or the obesity (and its metabolic context) that drives a lot of sleep apnea might also make the same people more prone to pain.

A huge 2020 study weighed in on that: Athar et al. looked at the medical records of 858,000 young veterans. At first glance, apnea and pain seemed clearly linked: 35% of the veterans with apnea reported significant pain, versus 27% without. But the apnea group was also older, heavier, and sicker in general, and once that was accounted for, the gap mostly evaporated — just a couple extra people in pain out of every hundred with apnea. With numbers that big, that little signal may well be real … but it’s little.

As for treatment, McCarthy et al. reviewed that evidence and found no sign that CPAP helps any chronic pain except headache — which apnea itself can cause.

And in 2025, Perea et al. rated most of the studies comparing pain patients with and without apnea as low quality — no clear signal.

A cynical principle: no clear evidence probably means no important link

The evidence is half-butted, but sometimes even inadequate evidence is informative: a clinically significant phenomenon is unlikely to be missed by several independent studies, even poor ones. The 2018 reviews found no clear relationship between apnea and pain, which suggested there probably isn’t a strong one — and that’s pretty much what the huge 2020 study found. They’re related only weakly and messily, if at all.

Obvious is obvious. A stronger correlation wouldn’t be this hard to confirm.