Your sleep study was “normal.” You’re still exhausted.
There may be a reason. Upper Airway Resistance Syndrome (UARS) is one of the most under-diagnosed sleep disorders in medicine — all the daytime consequences of sleep apnea, with a sleep report that reads as fine. The test was measuring the wrong thing.
What is Upper Airway Resistance Syndrome?
UARS is a form of sleep-disordered breathing in which the airway narrows enough to increase resistance and trigger arousal from sleep — but not enough to cause the oxygen drops or complete pauses that define obstructive sleep apnea. The brain detects the extra effort required to breathe against a narrowed airway and repeatedly rouses itself from deeper sleep stages to relieve the obstruction. The result is severely fragmented, non-restorative sleep.
These events are called Respiratory Effort-Related Arousals, or RERAs — brief surges in breathing effort that pull the brain out of deep sleep without ever registering as a standard apnea or hypopnea. UARS was first described by Dr. Christian Guilleminault at Stanford University, whose decades of work established that the airway does not need to collapse completely to disrupt sleep — resistance alone is sufficient — and that the structural dimensions of the jaw and airway, shaped during development, are central to susceptibility.
Because the AHI — the index most clinicians and insurers rely on — remains below the diagnostic threshold for sleep apnea, UARS patients are routinely told their sleep is fine. It is not.
The Apnea-Hypopnea Index (AHI) only counts complete apneas and qualifying hypopneas. The Respiratory Disturbance Index (RDI) adds RERAs. A UARS patient may have an AHI of 2 and an RDI of 18 — appearing “normal” on a standard report while experiencing 18 significant sleep disruptions every hour.
Who gets UARS?
UARS does not follow the demographic profile of typical sleep apnea. It disproportionately affects women of all ages, younger adults — including patients in their 20s and 30s — people with normal or low BMI, and people with narrow jaws, high arched palates, or retruded facial profiles. Because these patients don’t “look like” they have a sleep disorder, they cycle through the medical system for years. Common misdiagnoses include generalized anxiety, depression, fibromyalgia, chronic fatigue syndrome, IBS, and dysautonomia — all of which can coexist with UARS, but none of which are the cause.
What UARS actually feels like
Loud snoring and witnessed apneas — the hallmarks of sleep apnea — are often absent. Instead, UARS symptoms cluster around chronic sleep fragmentation and a nervous system stuck in overdrive:
- Chronic unrefreshing sleep despite adequate hours
- Severe daytime fatigue and brain fog
- Morning headaches
- Insomnia or difficulty staying asleep
- Anxiety and mood dysregulation
- Cold hands and feet (autonomic dysfunction)
- Irritable bowel syndrome or chronic GI issues
- Light or fragmented sleep
- Low blood pressure or orthostatic intolerance
- Heightened sensitivity to light, sound, and pain
- Snoring that is mild, intermittent — or absent entirely
If several of these describe you — and you’ve been told your sleep study is normal — UARS may be the explanation that has been missed.
Four ways a real disorder reads as “normal.”
A 'normal' AHI on the report
UARS patients rarely stop breathing completely. Their AHI is often below 5 — technically normal — so they are told their sleep study is fine. But the RDI, which counts RERAs, may be significantly elevated. Most sleep reports lead with AHI; many do not report RDI at all.
The 4% desaturation problem
A hypopnea only counts as an event if oxygen drops by a defined threshold. The AASM recommends 3%; many labs and insurers still apply 4%, which excludes more events and suppresses the AHI. A patient with true disease can be rendered 'normal' by this single scoring decision.
The demographics don't fit the stereotype
UARS disproportionately affects women, younger adults, and patients with normal or below-average BMI. Because sleep apnea is stereotypically an overweight man who snores, UARS patients are dismissed — or misdiagnosed with anxiety, depression, fibromyalgia, or chronic fatigue syndrome.
Home sleep tests miss it entirely
At-home tests (HSATs) don't record the cortical arousals that define RERAs — without EEG data they cannot be scored. A patient with significant UARS can receive a completely normal home sleep test. Full in-lab polysomnography with nasal pressure transducer recording is needed for the complete picture.
Treating UARS
UARS responds well to the same airway-focused interventions used for obstructive sleep apnea. Because UARS patients often have heightened autonomic reactivity, gentler modalities — particularly oral appliance therapy — frequently produce better compliance and outcomes than CPAP alone.
Oral appliance therapy
Custom appliances that advance the jaw or modify airway dimensions reduce the resistance that triggers RERAs. Many UARS patients respond exceptionally well to OAT — often better than to CPAP, because of their heightened arousal sensitivity. Many report transformative improvement within weeks.
Palatal expansion
A narrow palate reduces nasal airway volume and forces mouth breathing, which dramatically increases upper airway resistance. Expanding the palate — especially in younger patients — can reduce or resolve UARS at its structural root. In adults, surgically-assisted expansion (SARPE or MARPE) achieves the same change.
Myofunctional therapy
Normalizing tongue posture, lip seal, and nasal breathing reduces the soft-tissue factors behind airway resistance during sleep. Dr. Deal's "Big 3" — lips together, nasal breathing, tongue on the roof of the mouth — are foundational to any airway-focused treatment plan.
CPAP at low pressures
CPAP can be effective for UARS, but many patients with heightened autonomic reactivity find the positive pressure intrusive and hard to tolerate. Bilevel PAP or adaptive servo-ventilation may suit those who choose PAP therapy; oral appliance therapy is frequently the better-tolerated first line.
Wondering about oral appliance therapy specifically? Read the plain-language OAT explainer →
The research behind structural airway treatment
Building on Guilleminault’s foundation, Dr. Soroush Zaghi — Harvard Medical School graduate, ENT residency at UCLA, Sleep Surgery Fellow at Stanford, and Medical Director of The Breathe Institute in Los Angeles — has become one of the leading clinical researchers in UARS and sleep-disordered breathing. With over 97 peer-reviewed publications and more than 7,100 citations, his research connects structural airway anatomy — palatal width, tongue posture, tongue-tie, jaw position — to functional outcomes in UARS and OSA.
His 2016 maxillomandibular advancement meta-analysis (JAMA Otolaryngology) pooled 518 patients treated with jaw advancement surgery and found a mean AHI reduction of 80.1%, with 98.8% of patients improving. A separate maxillary expansion meta-analysis (Journal of Cranio-Maxillofacial Surgery, 2016) found AHI falling from 24.3 to 9.9 events per hour — a 59.3% reduction from palatal widening alone. And his 2025 study of 445 tongue-tie patients confirmed that lingual frenuloplasty paired with myofunctional therapy produces high satisfaction and durable outcomes.
The through-line: UARS and OSA are not merely soft-tissue problems. They are structural problems with structural solutions — expanding the jaw, establishing nasal breathing, releasing tethered oral tissues, and rehabilitating tongue posture address the architecture of the airway, not just its symptoms.
A note to patients who have been dismissed
If you have been through a sleep study, been told you are fine, and continue to suffer — your experience is real, and it is shared by many. The tools used to evaluate sleep have not kept pace with the science of sleep-disordered breathing. UARS exists at the edge of what standard testing measures, and the patients it affects are often the least likely to “look like” they have a sleep problem. We evaluate the complete picture: AHI and RDI, the desaturation threshold used in scoring, airway anatomy, craniofacial structure, and your full symptom history. If UARS has been missed in your case, we can find it — and treat it.