Upper Airway Resistance Syndrome: When Your Sleep Study Comes Back “Normal”
Some of the most exhausted patients we see have a sleep study showing an apnea-hypopnea index under 5 — technically normal. They have been told their sleep is fine. They do not feel fine. They wake unrefreshed, run on fumes by mid-afternoon, and often carry a collection of other symptoms that no one has connected: cold hands, lightheadedness on standing, anxiety, headaches, and a jaw that aches every morning.
Upper Airway Resistance Syndrome, or UARS, describes this picture. It is one of the more instructive conditions in airway medicine, because it demonstrates how a threshold designed to capture one problem can miss a related one.
What UARS Is
UARS was first characterized at Stanford in the early 1990s. The mechanism is increased resistance to airflow through the upper airway during sleep. The airway narrows, the effort required to breathe through it rises, and the brain responds by briefly lightening sleep — a respiratory effort-related arousal, or RERA — to restore airflow.
The crucial detail is that these arousals correct the problem before it produces the events a standard scoring threshold counts. Oxygen saturation may barely move. There may be no complete airway closure. What is disrupted is not oxygenation but sleep continuity: dozens or hundreds of brief arousals per night, most of which the patient never consciously registers, fragmenting sleep architecture and preventing the deeper restorative stages from consolidating.
The result is a person who spends eight hours in bed and receives a fraction of the recovery those eight hours should provide.
Why It Gets Missed
The apnea-hypopnea index counts apneas and hypopneas. RERAs are, by definition, neither. Scoring RERAs requires either esophageal manometry — rarely used outside research settings — or careful analysis of nasal pressure flow limitation and EEG arousals, which requires attended polysomnography with someone specifically looking for it. Home sleep apnea tests generally do not capture EEG at all, so arousals cannot be scored from them.
There is also a demographic problem. The recognizable profile for obstructive sleep apnea — older, heavier, male, loud snoring, witnessed pauses — leads clinicians to look. The typical UARS patient often looks nothing like that: frequently female, frequently slim, frequently young or middle-aged, often not a notable snorer. When symptoms don’t match the expected picture, they tend to be attributed to stress, anxiety, depression, or chronic fatigue.
The Symptom Pattern
UARS produces a recognizable cluster once you know to look for it:
• Persistent fatigue and unrefreshing sleep despite adequate time in bed
• Frequent awakenings, or waking without knowing why
• Sleep-onset or sleep-maintenance insomnia
• Morning headaches and morning jaw soreness
• Cold hands and feet
• Lightheadedness on standing, or a history of low blood pressure
• Anxiety, and a nervous system that seems to run hot
• Irritable bowel symptoms
• Bruxism
• Chronic nasal congestion or a longstanding habit of mouth breathing
• A history of orthodontic extractions, a narrow palate, or crowded teeth
The autonomic symptoms in that list — the cold extremities, the low blood pressure, the lightheadedness — are among the more distinctive features and are often the ones that have been most thoroughly ignored.
The Anatomy Behind It
The structural findings in UARS are usually visible on a dental examination, which is a large part of why dentists are well positioned to recognize the condition:
• A narrow or high, vaulted palate, which restricts the floor of the nose and reduces nasal cross-sectional area
• Dental crowding, or crowding that returned after orthodontic treatment
• A retruded mandible, which positions the tongue base further back
• Restricted tongue mobility, including tongue-tie
• Low resting tongue posture rather than contact with the palate
• Scalloped tongue borders, indicating the tongue is pressed against the teeth
• Enlarged tonsils, a long soft palate, or a crowded oropharynx
• Nasal obstruction from septal deviation, turbinate hypertrophy, or allergic rhinitis
These are structural findings. They do not resolve with sleep hygiene advice, and they are not explained by stress.
Where the Debate Sits
Honesty requires acknowledging that UARS is not universally treated as a separate diagnosis. Current sleep medicine classification largely folds it under obstructive sleep apnea as part of a spectrum of sleep-related breathing disorders, on the reasonable argument that the underlying mechanism is the same and the distinction is one of degree.
That is a fair position taxonomically. Our concern is practical: patients whose studies fall below the apnea threshold are frequently discharged without treatment, and the label is what determines whether anyone acts. Whether you call it UARS or mild sleep-disordered breathing matters less than whether the flow limitation and arousals are identified and addressed.
Related reading: What Is an Airway-Focused Dentist? A Plain-English Explanation.
How It Should Be Evaluated
If your symptoms fit this pattern and your sleep study was reported as normal, several things are worth pursuing:
• Ask for the full sleep study report, not the summary line. Look for whether RERAs were scored, whether flow limitation was described, what the arousal index was, and whether the study was attended or home-based. An arousal index that is high with a low AHI is a meaningful finding.
• Consider attended polysomnography if your prior test was a home study, since home studies cannot score arousals.
• Get an airway-focused structural examination — palate width and vault height, tongue posture and mobility, tonsil grade, nasal patency, mandibular position, and dental wear patterns.
• Obtain 3D imaging to assess nasal airway volume, the pharyngeal airway, and the skeletal relationships that shape both.
• Involve an ENT when nasal obstruction appears to be a significant contributor. Nasal resistance is often the first domino, and it is frequently correctable.
Treatment Approaches
Because UARS is primarily a resistance problem, treatment aims at reducing that resistance:
• Nasal airway treatment first when nasal obstruction is present. Improving nasal breathing is foundational, and everything else works better once it is addressed.
• Maxillary expansion in appropriate adult candidates, which widens the palate and the floor of the nose. In our practice this means MARPE for adults whose midpalatal suture has fused; in children and adolescents, conventional expansion.
• Myofunctional therapy to establish nasal breathing, proper tongue posture, and correct swallowing patterns.
• Oral appliance therapy to hold the mandible forward and increase pharyngeal space, coordinated with a sleep physician.
• Airway-directed orthodontics, including aligner therapy planned to develop arch form and create room for the tongue rather than to achieve a purely cosmetic result.
• Positional and behavioral measures as adjuncts, including alcohol timing and sleep position.
Improvement in this group is measured in how patients feel and function — sleep quality, daytime energy, morning symptoms — supported by repeat objective testing where it is available.
Frequently Asked Questions
Can UARS progress to obstructive sleep apnea? Longitudinal data are limited, but the two exist on a continuum and share the same anatomical drivers, so progression is plausible. Weight gain, aging tissue changes, and worsening nasal obstruction all move a patient along that spectrum.
Is CPAP used for UARS? It is sometimes prescribed and can be effective, though tolerance is often poor in this group because the perceived problem is subtler and the pressure requirement is low. Structural and dental approaches are frequently a better fit.
My doctor says my sleep study was normal. Is a dental evaluation contradicting that? No. The study measured what it was designed to measure, and reported it accurately. An airway-focused dental examination looks at anatomy and function that a scoring index does not capture. The two are complementary, and we routinely share findings back with the referring physician.
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About Joint & Airway Analytics
Joint & Airway Analytics is a TMJ, airway, and craniofacial pain practice in San Jose, California, founded and directed by Victor D. Woodlief, DMD. The practice focuses on temporomandibular disorders, sleep-disordered breathing, and orofacial pain, and treats patients from San Jose, Campbell, Los Gatos, Saratoga, Cupertino, Santa Clara, Willow Glen, and the wider Bay Area.
Joint & Airway Analytics
385 S. Monroe Street, San Jose, CA 95128
Phone: (408) 516-1432
Website: www.airwayhealth.net