Ask people to name a disorder that interferes with a good night’s shut-eye, and chances are obstructive sleep apnea (OSA) is what you’ll hear.

But a little-known condition—often referred to as OSA’s “silent sister”—also leads to unexplained daytime fatigue and can even contribute to seemingly unrelated health problems (see below). The problem is, the typical red flags that patients—and doctors—look for when zeroing in on a sleep disorder, such as loud snoring and gasping during sleep, often are missing. 

This mysterious sleep saboteur is called upper airway resistance syndrome (UARS). Like OSA, it causes multiple, micro-awakenings that occur when the sufferer unconsciously senses difficulty breathing while sleeping. The person will soon fall back to sleep only to awaken again, seconds or minutes later. This cycle can continue throughout the night—without the sufferer (or bed partner) even realizing it. But there are subtle differences between OSA and UARS. What you need to know…

How to Detect This “Silent” Disorder

No one knows exactly how many people have UARS. However, in a study of 527 subjects in a military hospital who had daytime fatigue, the prevalence was 8.4%, according to research published in the journal Chest.

Unlike OSA, in which breathing completely stops for tens of seconds at a time, breathing is merely impaired with UARS. The condition can be caused by a naturally narrowed airway (as may occur in a person who is thin)…an ill-positioned tongue (if it relaxes and partially covers the airway)…or loose throat tissues that interfere with breathing.

Some people with UARS go on to develop OSA, but many do not. As a result, these individuals can have UARS for years (or even a lifetime) without it being diagnosed and treated.

When UARS goes undetected, the repeated micro-awakenings cause sufferers to become not only tired and stressed in the daytime but may also make them highly sensitive to emotional triggers, light, sounds and weather changes. 

The ongoing anxiety that so often accompanies UARS also can lead to tension headaches and depression. In research published in Respiration, the continual stress and lack of restorative sleep that mark UARS have been linked to the development of digestive symptoms, such as irritable bowel disease, and increased cardiovascular risks due to blood pressure spikes that can occur with the repeated micro-awakenings.  

Do You Have This Disorder?

If you have daytime fatigue, with or without the health problems that can accompany UARS, consider seeing a dentist or a sleep specialist who is familiar with the disorder—not all physicians are. Before scheduling an appointment, call the physician’s office and ask whether he/she treats UARS. 

A knowledgeable specialist will inspect the back of the mouth, nose and jaw to see whether the person’s airway appears unobstructed to the eye. A surprising clue: Crooked teeth or a “scalloped” tongue, in which ridges or indentations on the sides of the tongue indicate where it pushes against the molars, can indicate a crowded jaw and partially obstructed airway.  

If UARS is suspected, the next step is a sleep study, in which the number and frequency of respiratory effort-­related arousals (RERAs) are monitored. These arousals from sleep do not technically meet the definition of apneas (pauses in breathing) or hypopneas (periods of shallow breathing), both of which occur with OSA. Note: A sleep study performed in a lab is more sensitive to the subtle obstructions that accompany UARS than in-home studies.

If apneas and hypopneas last for more than 10 seconds, they qualify as a sleep breathing event, and more than five such events an hour points to OSA if you have other symptoms such as daytime sleepiness, cognitive dysfunction or high blood pressure. When the patient does not have OSA, a high number of RERAs may suggest UARS. 

Recent development:A procedure called drug-induced sleep endoscopy has emerged as a useful technique for diagnosing UARS. With this procedure, which is performed with the patient under sedation, a surgeon will insert a small camera through the nose into the airway to view any blockages that affect breathing during sleep.  

3 Self-Care Measures 

Even without an official diagnosis, people who suffer from unexplained daytime fatigue and suspect that they may have UARS can take steps to improve the disorder. For example…

  • Don’t eat within three hours of bedtime. Here’s why: When a person with UARS has difficulty breathing, stomach juices get sucked up into the throat causing swelling and more obstruction. Meal timing helps prevent this.
  • Choose the right sleep position. Sleeping on your side or stomach (though this can trigger back pain in some people) helps many individuals with UARS. When sleeping on your back, it’s easy for the tongue to fall back into the throat area and partially block the airway. 
  • Try simple oral exercises. Strengthening your airway muscles will help prevent UARS by reducing the odds that the muscles will collapse and impair breathing. What to do: With an exercise called the “tongue slide,” you push the tip of your tongue against the roof of your mouth and slide your tongue backward and forward, repeating the motion 20 times. Do this several times daily while working or watching TV. 

When More Help Is Needed

If the steps above aren’t adequate, you may need one of the following…*

  • Mouth guard. If your dentist thinks you may have UARS due to a misaligned jaw, you can be fitted with a personalized mouth guard—known as a mandibular advancement device (MAD)—that slightly pushes the lower jaw and tongue forward to hold the airway open when the throat muscles relax. This prevents the airway from collapsing during deep sleep. 
  • Bone-growth appliance. Some dentists can fit an orthodontic device (known as an anterior growth guidance appliance), which can stimulate bone growth by allowing the jaw to expand outward, ultimately providing more space to breathe while sleeping. It is usually worn all day and night for up to two years. 
  • CPAP. Continuous positive airway pressure (CPAP) devices send a constant flow of air pressure into the throat to ensure that the airway stays open during sleep. CPAP is usually used for OSA but also helps relieve UARS. 
  • Surgery. The most definitive treatment for UARS is surgery to physically alter the anatomy of the breathing airway. This may involve, for example, stiffening of loose palate tissue and/or the placement of an implant. 

The good news is that people who have been successfully treated for UARS report waking up refreshed, as well as having a better quality of life and a reduced risk for the health problems related to this disorder.

*Most insurers do not cover these treatments unless UARS progresses to OSA.