What Is Upper Airway Resistance Syndrome (UARS)?

Mild Sleep Apnea Condition May Cause Arousals, Sleepiness

Women may be more likely to experience upper airway resistance syndrome (UARS)
Women may be more likely to experience upper airway resistance syndrome (UARS). EMS-FORSTER-PRODUCTIONS/Getty Images

Sometimes snoring and mild disturbed breathing in sleep can present subtly. It may not be obvious to the affected person, or to her bed partner, and it may even evade detection with standard sleep testing. There is some controversy about whether upper airway resistance syndrome (UARS) is a distinct disorder or even whether it is part of the spectrum of sleep-related breathing disorders that includes sleep apnea.

What is UARS and how might it affect your sleep? 

Defining Upper Airway Resistance Syndrome

Upper airway resistance syndrome (UARS) is believed to be a disorder of increased airway resistance without the classic findings suggestive of sleep apnea. It may be associated with snoring, fragmented sleep with nocturnal awakenings, teeth grinding or clenching (bruxism), increased urination at night (nocturia), daytime sleepiness, concentration problems, and mood disturbances. It may occur more often in younger women and in people who have a thin or average build.

Generally, in sleep apnea there is a significant reduction in airflow (with a greater than 30% reduction from baseline) and associated drops in the oxygen levels of the blood or awakenings from deep to lighter sleep or wakefulness. There may be a complete cessation in breathing - which is called apnea - or a partial reduction called a hypopnea.

In upper airway resistance there is not sufficient decrease in airflow to be called either hypopneic or apneic events, and there are no drops in the oxygen levels of the blood.

Nevertheless, there is often snoring and frequent brief arousals noted in sleep with significant excessive daytime sleepiness.

It is thought that the frequent arousals associated with the condition lead to the sleepiness. These arousals may be due to a modestly increased effort to breathe, which can be detected with measurement of pressure changes within the esophagus using a pressure esophageal manometer (pes study).

Diagnosis and Treatment of UARS

Diagnosis of upper airway resistance syndrome is accomplished with careful documentation of increasingly negative esophageal pressures occurring before the associated arousals. This may be done with adjunctive measurements associated with a standard sleep study called a polysomnogram. The insertion of a pediatric feeding tube from the nose to the upper airway (behind the tongue) may detect increased pressures corresponding with effort to breathe. This pes study is not performed as part of most sleep studies and may require referral to specific sleep specialists. Though uncomfortable, this information may prove invaluable and will allow some individuals to qualify for additional treatment.

The treatment of UARS is similar to obstructive sleep apnea. Individuals afflicted with UARS may respond to continuous positive airway pressure (CPAP) therapy or other alternative treatments. The use of an oral appliance may be effective.

Fortunately, even though UARS may be considered on the mild end of the sleep apnea spectrum, treatments can be equally important. By getting less disrupted sleep, the symptoms associated with the condition can resolve.


1. Guilleminault C, et al. "A cause of excessive daytime sleepiness. The upper airway resistance syndrome." Chest 1993;104(3):781-787.

2. Kryger, MH et al. "Principles and Practice of Sleep Medicine." Elsevier, 5th edition.

3. Shepard JW, Jr., et al. "Evaluation of the upper airway in patients with obstructive sleep apnea." Sleep 1991;14(4):361-371.

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