I'm a Sleep Physician. I Spent 100 Nights Investigating the DERYTHM Pro After a Patient Walked In Having Quit His CPAP — and His Numbers Got Better. Here's What I Found.

Another sleep gadget, or actual science? I had to know before I'd say a word to my patients — so I tested it on myself.

By Dr. Andrew Mercer, Sleep & Respiratory Physician

Updated 2026

When Mr. K came in for his annual review last autumn, I was expecting the usual conversation.

Higher pressure. A new mask. Maybe the word "surgery."

I pulled up his follow-up sleep study. Then I pulled up last year's to compare.

His AHI — the number of times his airway collapsed per hour — had dropped. Not because the machine was working harder. Because he'd stopped using the machine three months earlier.

"What on earth have you been doing?" I asked.

He reached into his bag and put a small black device on my desk. "My daughter found this. Sits under my chin. No mask."

I've been reading sleep studies for over twenty years. Airways don't get stronger. They get weaker, we prop them open with pressure, and eventually we cut. That is the entire model I was trained in.

But I couldn't argue with the number on my own screen.

The question every one of my patients is now asking

For months my inbox has carried the same line: "Is this chin device real, or is it another scam?"

I've prescribed every option there is — CPAP, mouth splints, referrals for surgery. So when a device claiming to fix the cause started circulating among my own patients, I was as sceptical as anyone.

Then I did what took some digging: I asked around my own practice. Four other patients were quietly using one. They'd never mentioned it — they assumed I'd wave it off as gimmickry. I pulled their studies too.

Every one showed improvement or held steady off the machine.

So I stopped guessing and investigated it properly.

The 100-night investigation

I wasn't going to trust marketing. I wanted evidence. So I:

• Read the published literature on airway-muscle training and stimulation
• Reviewed the trials behind the regulator-approved muscle-stimulation devices
• Followed 15 of my own patients through their first 90 days
• Wore one myself, every night, for 100 nights — because I snore, and I wanted to feel what my patients were feeling

What I found: the airway is a muscle — and muscle can be retrained

Here's what I had to sit with.

Obstructive sleep apnoea isn't fundamentally an air problem. It's a muscle problem. A band of muscles at the back of the throat — chiefly the genioglossus — is meant to hold the airway open while you sleep. With age, and for women after menopause as hormone support falls away, that muscle loses tone. It sags, the airway collapses, and you snore or stop breathing — dozens of times an hour.

CPAP doesn't change that muscle. It splints the airway with pressure. The moment the mask comes off, the throat is exactly as weak as before. It manages the symptom, brilliantly, for one night at a time — for life.

But the muscle itself? The published evidence says it can be trained.

In 2009, a randomised trial in the American Journal of Respiratory and Critical Care Medicine (Guimarães et al.) had moderate-OSA patients do daily throat-muscle exercises for three months. Their AHI fell by roughly 39% — no machine, no surgery.

The problem was adherence — nobody keeps up tongue drills for months. So medicine electrified the muscle instead. In 2014 the FDA approved hypoglossal nerve stimulation (a surgical implant, around $30,000) that fires the airway muscle to keep it open. It works — because it engages the actual muscle.

Then in 2021 the FDA cleared a non-surgical neuromuscular electrical-stimulation device for snoring and mild apnoea — proving you don't need the implant or the mask to train that muscle.

Neuromuscular electrical stimulation (NEMS) isn't fringe — physios have used it for decades to rebuild wasted muscle after strokes and injuries. Applying it to the airway dilators is the new part. It's not masking the symptom. It's retraining the machinery that stopped working.

What I actually observed

I'll be careful here, because I'm a physician and I won't overstate what I saw.

Of the 15 patients I followed, most reported quieter snoring and better mornings within the first several weeks; several who repeated a study showed a lower AHI than their pre-device baseline. It was not universal, and it was not overnight — it took weeks, as retraining any muscle does.

My own experience: by about week six my wife told me the snoring had stopped. I stopped waking at 3am. I stopped reaching for coffee at 3pm.

Is this a cure? No. Is it a controlled trial? No. But it's consistent with everything the published mechanism predicts — and that's more than I can say for most of what crosses my desk.

Why your doctor hasn't mentioned it

An uncomfortable truth: the DERYTHM Pro isn't a prescription. Which means —

• No pharmaceutical company profits from it
• No rep is educating sleep clinics about it
• No billing code, no place in the protocol
• No reason it appears at the conferences we attend

I surveyed colleagues in my network. Almost none had considered muscle stimulation for their at-home patients — not because the science isn't there, but because it lives outside the system we're trained inside. Curricula update on a twenty-year lag. If a drug rep doesn't bring it, most of us never hear it.

The problems with the standard path nobody says out loud

The progression problem

CPAP controls tonight. It doesn't strengthen anything. The underlying muscle keeps wasting, so the pressure creeps up year after year.

The stacking problem

Standard mask → higher pressure → full-face mask → mouth splint "for travel" → referral for surgery. Add, adjust, escalate. Never finish.

The cost problem

A machine, masks, filters, hoses, distilled water — for life. And the one approach that engages the muscle surgically, the implant, runs north of $30,000.

The tolerance problem

Around half of patients can't stick with CPAP — the claustrophobia, the dryness, the marks, the noise. They quit, and go back to untreated apnoea, which is the most dangerous place of all.

My professional assessment

After 100 nights, and following my own patients: for people with snoring and early-to-moderate apnoea, retraining the airway muscle addresses the cause, where CPAP manages the consequence.

CPAP is faster at masking the number. But root vs. symptom, no mask, no hose, no surgery, and a fraction of the lifetime cost? For the right person, it's not a difficult call.

What it actually is — no mystery

The DERYTHM Pro is a small, featherlight device that rests under the chin during sleep. It delivers gentle NEMS micro-pulses to the muscles supporting the airway — enough to recruit and progressively strengthen them, not enough to wake you. No mask. No hose. No mouthpiece. No implant. You turn it on, you sleep, it works. That's the whole of it — no proprietary mystery, no fairy tale.

Who it's for

• Snorers who've been told "it's just snoring"
• People on CPAP who can't stand it — or wear it and still wake exhausted
• People whose numbers keep climbing despite compliance
• People weighing up a mouthguard or surgery
• Anyone who wants to fix the cause, not rent a nightly workaround

My recommendation

If you snore, or you have early-to-moderate apnoea, or you're on a machine you hate — it is, in my professional opinion, worth 100 nights of your time to find out whether retraining the muscle works for you. It comes with a 100-night money-back guarantee, which removes essentially all the risk.

Please note: this is not a cure, and it is not a reason to stop CPAP without your doctor. If your numbers improve, take them to your doctor and discuss what's next. That's the right path.