Sleep problems are dangerous. In fact, sleep disorders can be deadly by contributing to car accidents and long-term health problems.
Sleep apnea symptoms are well known, but a related condition called upper airway resistance syndrome (UARS) also causes daytime fatigue. UARS is equally important to diagnose and treat.
UARS: No Apneas, But Lots of RERAs
Sleep apnea first came to the attention of doctors in the 1970s, but UARS was unrecognized until the early 1990s.
Both conditions lead sufferers to feel tired, even after a full night's sleep. Both conditions are caused by difficulty breathing during the night, as the soft tissue in the back of the throat relaxes and collapses, clogging the airway.
Sleep apnea is somewhat easier to diagnose than UARS. In sleep apnea, the sleeper's airflow decreases to 50% of normal (hypopneas) or the sleeper stops breathing completely (apneas).
In UARS, however, the brain reacts promptly to difficulties breathing. The brain nudges the sleeper awake for a moment. The sleeper shifts position, resumes breathing and goes back to sleep.
The goods news for UARS sufferers is that UARS doesn't cause ten-second apneas like sleep apnea does. Sleeping blood oxygen levels remain normal all night. That’s good for the sleeper's heart and cardiovascular system.
The bad news is that UARS can still ruin sleep. Every time the sufferer wakes up slightly, he or she loses the chance to have deep, restorative sleep.
In the morning, the sufferer probably won’t remember most of these small wakings, known as respiratory effort-related arousals (RERAs). The body remembers them, though, and they cause daytime fatigue. Without uninterrupted stretches of sleep, the body can’t achieve the deep slow-wave sleep that it needs.
Sleep Apnea or UARS?
Anyone suffering from daytime fatigue should have a sleep study to check for sleep apnea or UARS. During a sleep study, sensors monitor and record the details of nighttime breathing, brain activity, heart-rate and movements.
The results will show how many apneas and hypopneas the sleeper experiences per hour. This number is called the respiratory distress index (RDI) or the apnea-hypopnea index (AHI).
The sleep study will also reveal two other important numbers: blood oxygen levels and the number of RERAs per hour.
Three things make the difference between sleep apnea symptoms and UARS symptoms:
- In UARS, the RDI is in the normal range, five per hour or below. Someone with sleep apnea usually has an index of 15 or higher.
- In UARS, blood oxygen levels remain in the normal range (90% and above) rather than fluctuating.
- Unfortunately, in UARS, the sleeper experiences a high number of RERAs, at least 10 per hour. To identify RERAs, a doctor must look at your brain wave patterns during the night, as recorded in an electroencephalogram (EEG).
RERAs only appear in a sleep study that includes an EEG to measure brain activity. As a result, UARS may not appear in sleep studies conducted at home with a portable recording device. Home studies can collect data on breathing and blood oxygen but not brain activity.
Even though home sleep studies are more comfortable, the inconvenience of an overnight sleep study in a lab is worth it for anyone who suspects UARS.
Sleep Well Despite UARS
UARS is stealthy. Compared to sleep apnea, it affects more women and people of younger ages, even children. (Women's symptoms may differ from men's; read more here.) It doesn’t always cause snoring. And it doesn’t show up in yearly physicals by causing high blood pressure. UARS does show up in fatigue and reduced quality of life, however.
Treatment for UARS is similar to treatment for sleep apnea. In fact, some doctors suggest that UARS and sleep apnea are part of a “spectrum of diseases,” with UARS possibly leading to sleep apnea later in life.
Possible treatments are weight loss, C-PAP, oral appliances and surgery. Because doctors do not yet understand UARS as well as sleep apnea, sufferers may have to visit the doctor several times to find the right treatment. But for people who suffer from daytime fatigue, the search for a cure is worth it.
Those who suspect they have a sleep disorder should calculate their fatigue score, consult a doctor and consider scheduling a sleep study.
Sources:
Budev, Marie M. and Joseph A. Golish, ClevelandClinic.org, “Sleep-Disordered Breathing” (accessed May 13, 2010).
NHLBI.NIH.gov, "Sleep Apnea" (accessed May 13, 2010).
Jessamine Price - Jessamine Price is a writer, educator and world traveler who holds a Master of Philosophy in history from the University of Oxford (2000). ...
