Respiratory Effort-Related Sleep Arousal (RERA)

What Is a Respiratory Effort-Related Arousal (RERA)?

A respiratory effort-related arousal (RERA) Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. UpToDate delivers evidence-based clinical decision support that is clear, actionable, and rich with real-world insights. View Source is a temporary awakening from sleep that occurs after 10 or more seconds of decreased nasal breathing. 

When breathing slows, it can trigger a brief arousal so that normal breathing can be resumed. Even though sleepers usually do not remember these awakenings, the disruptions can throw off sleep cycles and worsen sleep.

RERAs can only be detected Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. UpToDate delivers evidence-based clinical decision support that is clear, actionable, and rich with real-world insights. View Source during an in-clinic sleep study that monitors breathing and brain activity. The sensors used in a sleep study can show RERAs, which involve a drop in airflow through the nose followed by a spike in brain activity caused by a partial awakening . 

RERA vs. Other Sleep-Related Breathing Disruptions

RERAs are not the only type of sleep disruptions caused by irregular breathing. When testing for sleep apnea, RERAs are distinguished from apneas and hypopneas. 

• Apneas: Apneas involve significant pauses in breathing. To be classified as an apnea, a person’s breathing must slow by 90% or more for at least 10 seconds.
• Hypopneas: Hypopneas are partial reductions in breathing. During a sleep study, hypopneas are identified when breathing slows by 30% or more for a period of at least 10 seconds, leading to a brief awakening or a 3% drop in blood oxygen levels.
• RERAs: Breathing reductions in RERAs are more mild than with apneas or hypopneas. RERAs involve 10 or more seconds of decreased nasal breathing immediately followed by an arousal from sleep. 

While apneas, hypopneas, and RERAs all indicate a slowing of breathing during sleep, an important difference is that RERAs do not involve a drop in blood oxygen levels.

A person whose sleep disruptions are mostly RERAs may be described as having a subtype of OSA called upper airway resistance syndrome (UARS). Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. UpToDate delivers evidence-based clinical decision support that is clear, actionable, and rich with real-world insights. View Source Among people with OSA, those with UARS usually have more mild sleep fragmentation. They may also be less likely to have cardiovascular complications Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source since they do not have repeated drops in their blood oxygen levels during sleep. 

Causes of RERA

Like apneas and hypopneas, RERAs are caused when breathing is restricted by a narrowing of the upper airway. These sleep disruptions repeatedly occur during the night in people with OSA. 

RERAs are more common in people with certain facial features Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. UpToDate delivers evidence-based clinical decision support that is clear, actionable, and rich with real-world insights. View Source that inhibit airflow through the nose. Some other factors that can increase the risk of OSA include nasal congestion, obesity, and being of an older age.

Symptoms of RERAs

When a person experiences multiple RERAs during the night, it can interfere with their sleep. Symptoms of recurring RERAs can include: 

• Snoring that may involve snorting or choking 
• Waking up unrefreshed
• Excessive fatigue or sleepiness during the day 
• Difficulty concentrating or thinking 

Other potential symptoms of obstructive sleep apnea, which frequently involves RERAs and other breathing disruptions, include: 

• Dry mouth 
• Morning headaches 
• Having a hard time staying asleep through the night 
• Frequent urination at night 

Anyone with these symptoms should talk with a doctor to determine whether they may be caused by OSA. 

Diagnosing RERA

The only way to dependably identify RERAs is to do an overnight sleep study in a sleep lab. During the study equipment tracks various bodily functions, including brain activity, sleep stages, and breathing. With this data, a sleep technician can detect apneas, hypopneas, and RERAs.

However, not all sleep studies include a count of RERAs. In some labs, only apneas and hypopneas are considered when diagnosing sleep apnea. 

Many sleep labs report a metric called the respiratory distress index (RDI), which is the combined total of apneas, hypopneas, and RERAs divided by the time a person spent sleeping. The apnea-hypopnea index (AHI) is a similar calculation that does not include RERAs. Both the AHI and RDI can be used to assess the severity of sleep apnea, but there is no consensus among experts about which metric is most useful.

Although home sleep apnea tests can diagnose OSA in some people, these tests cannot measure RERAs because they do not monitor brain activity. Positive airway pressure (PAP) devices, like CPAPs, also cannot measure RERAs.

Treatment for RERA 

Isolated or infrequent RERAs may not require treatment. However, treatment may be needed when RERAs occur as part of OSA and when they cause significant sleep disruptions.

For people with OSA, the goal of treatment is to eliminate as many apneas, hypopneas, and RERAs as possible. One of the most common treatments involves using a continuous PAP (CPAP) or auto-adjusting PAP (APAP) device during sleep. These devices send pressurized air into the upper airway to prevent breathing from being restricted.

Other approaches to treating OSA and RERAs may include:

• Wearing a custom-fitted oral appliance during sleep 
• Making behavioral changes like losing weight, changing sleep position, and avoiding alcohol before bed 
• Having surgery to implant a device to stimulate nerves that affect muscles around the airway 
• Having surgery to remove or modify tissue that can block the airway 

Not all of these treatments are viable options for everyone with OSA or RERAs. It is important to consult with a doctor about the most appropriate treatment in any specific person’s situation.