Respiratory effort-related arousals, or RERAs, are brief awakenings from sleep triggered by 10 or more seconds of decreased nasal breathing that fragment your sleep and cause daytime drowsiness, even though you won't remember waking up. Unlike more severe breathing disruptions, RERAs don't involve dangerous drops in blood oxygen levels, but they can still wreck your sleep quality and leave you exhausted during the day.

What Exactly Is a RERA and How Does It Differ From Sleep Apnea?

When your breathing slows during sleep, your brain briefly wakes you to restart normal breathing. These micro-awakenings are RERAs, and they're one type of breathing-related sleep disruption associated with obstructive sleep apnea (OSA). The key difference between RERAs and other breathing problems comes down to severity.

RERAs involve mild reductions in airflow through the nose, while more serious breathing disruptions include apneas and hypopneas. An apnea is a significant pause in breathing where airflow drops by 90% or more for at least 10 seconds. A hypopnea is a partial reduction in breathing where airflow slows by 30% or more for at least 10 seconds, often causing a brief awakening or a 3% drop in blood oxygen levels. RERAs, by contrast, involve milder breathing reductions without the dangerous oxygen drops.

People whose sleep disruptions are mostly RERAs may have a subtype of OSA called upper airway resistance syndrome (UARS). Those with UARS typically experience milder sleep fragmentation and are less likely to develop cardiovascular complications since they don't have repeated drops in blood oxygen during sleep.

What Symptoms Should You Watch For?

The tricky part about RERAs is that you won't know they're happening. You won't remember waking up, but your sleep partner might notice something's off. If you experience multiple RERAs throughout the night, watch for these warning signs:

• Snoring Patterns: Snoring that may involve snorting or choking sounds, which often prompts sleep partners to notice something is wrong.
• Morning Symptoms: Waking up unrefreshed despite spending a full night in bed, or experiencing morning headaches that fade after a few hours.
• Daytime Effects: Excessive fatigue or sleepiness during the day, difficulty concentrating or thinking clearly, and struggling to stay awake during routine activities.
• Sleep Disruption: Having a hard time staying asleep through the night, frequent urination at night, or a dry mouth upon waking.

If you notice any combination of these symptoms, it's worth talking to a doctor to determine whether RERAs or another sleep disorder might be the culprit.

How Are RERAs Actually Diagnosed?

The only reliable way to identify RERAs is through an overnight sleep study in a sleep lab. During the study, equipment tracks your brain activity, sleep stages, and breathing patterns. A sleep technician can then detect apneas, hypopneas, and RERAs by analyzing the data.

However, not all sleep labs count RERAs when diagnosing sleep apnea. Some labs only consider apneas and hypopneas. Many sleep labs report a metric called the respiratory distress index (RDI), which combines the total of apneas, hypopneas, and RERAs divided by your sleep time. The apnea-hypopnea index (AHI) is a similar calculation that doesn't include RERAs. Both metrics can assess sleep apnea severity, though experts don't fully agree on which is most useful.

Home sleep apnea tests cannot measure RERAs because they don't monitor brain activity, and CPAP devices also cannot measure RERAs. This is why an in-lab study is essential if you suspect RERAs are disrupting your sleep.

How to Manage RERAs and Improve Your Sleep

Isolated or infrequent RERAs may not need treatment, but when they occur as part of OSA and cause significant sleep disruptions, several approaches can help:

• Positive Airway Pressure Devices: Continuous PAP (CPAP) or auto-adjusting PAP (APAP) devices send pressurized air into your upper airway to prevent breathing from being restricted, eliminating most RERAs and improving daytime alertness.
• Oral Appliances: Custom-fitted oral appliances worn during sleep work like a retainer and keep your upper airway open, offering an alternative to CPAP for some people.
• Behavioral Changes: Losing weight, changing your sleep position, and avoiding alcohol before bed can reduce the frequency of RERAs by opening your airway more effectively.
• Surgical Options: Surgery to implant a device that stimulates nerves affecting airway muscles, or surgery to remove or modify tissue blocking the airway, may help in specific cases.

The best treatment depends on your individual situation, so it's important to work with a doctor to find the right approach for you.

Why RERAs Matter More Than You Might Think

RERAs are more common in people with certain facial features that inhibit airflow through the nose, as well as in those with nasal congestion, obesity, or older age. Even though RERAs don't cause the dangerous oxygen drops associated with more severe sleep apnea, they still fragment your sleep architecture and prevent you from getting the restorative rest your body needs.

The cumulative effect of multiple RERAs throughout the night can leave you feeling exhausted, foggy, and unable to concentrate, even if you spent eight hours in bed. If you suspect RERAs might be disrupting your sleep, don't wait to mention it to your doctor. A simple overnight sleep study can reveal whether these hidden breathing glitches are sabotaging your rest and your daytime performance.