Sleep apnea is a common sleep disorder where breathing repeatedly stops and starts throughout the night. These interruptions can lead to fragmented sleep and reduced oxygen levels in the blood. While sleep apnea can occur at any point during sleep, its characteristics and impact can differ depending on the specific sleep stage. Understanding these variations, particularly in relation to rapid eye movement (REM) sleep, is important for diagnosis and effective management.
The Role of REM Sleep in Apnea
REM sleep is a distinct stage characterized by rapid eye movements, vivid dreaming, and a temporary paralysis of most muscles, known as muscle atonia. Although the brain is highly active, similar to wakefulness, the body remains largely still, preventing individuals from acting out dreams. This stage makes up approximately 25% of total sleep time in healthy adults.
Physiological changes during REM sleep increase susceptibility to apnea events. The muscle atonia, particularly affecting the genioglossus muscle in the tongue, leads to increased collapsibility of the upper airway. There is also a reduction in the body’s ventilatory drive, meaning the brain’s signals to breathe are less responsive to changes in oxygen and carbon dioxide levels. These combined factors result in more frequent, longer, and more severe drops in blood oxygen saturation during apneas in REM sleep compared to non-REM sleep.
Identifying Symptoms and Risk Factors
Symptoms of REM sleep apnea often resemble those of general sleep apnea but can be particularly pronounced. Loud snoring, especially when accompanied by noticeable pauses in breathing, gasping, or choking sounds, are common indicators. Individuals may also experience excessive daytime sleepiness, morning headaches, and difficulty concentrating due to fragmented sleep.
Several factors increase susceptibility to sleep apnea, including the REM-predominant form. Obesity is a significant risk factor, as excess tissue around the neck narrows the airway. Males generally have a higher prevalence of sleep apnea, although REM sleep apnea may be more common in women. Advancing age, a family history of sleep apnea, and specific anatomical features like a recessed chin, large tonsils, or a large tongue also contribute to airway obstruction.
Diagnosing REM Sleep Apnea and Its Health Impact
Diagnosing REM sleep apnea involves an overnight sleep study (polysomnography or PSG). This comprehensive test monitors various bodily functions during sleep, including brain waves, eye movements, muscle activity, heart rate, breathing patterns, and blood oxygen levels. PSG allows healthcare professionals to identify when apnea events occur and during which sleep stages.
A higher Apnea-Hypopnea Index (AHI) during REM sleep compared to non-REM sleep is indicative of REM sleep apnea. The AHI measures the average number of apneas (complete breathing cessation) and hypopneas (partial reduction in airflow) per hour of sleep. Diagnosis often involves an AHI during REM sleep at least twice that of non-REM sleep.
Untreated REM sleep apnea can lead to various health consequences due to repeated drops in oxygen and sleep fragmentation. It is associated with systemic hypertension (high blood pressure) and increased cardiometabolic risk, including heart attack, stroke, and heart failure. There can also be an association with impaired glucose metabolism and type 2 diabetes. Furthermore, it can negatively impact cognitive function, leading to memory decline, and contribute to mood changes like depression.
Effective Treatment Strategies
Continuous Positive Airway Pressure (CPAP) therapy is an effective treatment for sleep apnea, including the REM-predominant form. CPAP machines deliver a continuous stream of air through a mask, creating positive pressure that keeps the airway open and prevents collapse. For REM sleep apnea, consistent use of CPAP throughout the night is recommended, as REM sleep tends to occur more in the latter half of the night.
Oral appliances offer an alternative or supplementary treatment option. These custom-fitted mouthpieces reposition the jaw forward or hold the tongue in place to maintain an open airway. Lifestyle modifications are also important components of treatment. Weight loss can significantly reduce the severity of sleep apnea, as can positional therapy, which involves sleeping on one’s side to prevent airway collapse. In select cases where other treatments are not effective or suitable, surgical interventions may be considered to address anatomical obstructions in the airway.
Treatment plans are individualized to best suit the patient’s specific needs and the characteristics of their sleep apnea.