The importance of arousal in obstructive sleep apnea—updates from the American Thoracic Society 2016

The mechanism underlying obstructive sleep apnea (OSA) is thought to vary across individuals (1). OSA patients are anatomically predisposed to airway collapse but pharyngeal dilator muscle reflexes can help to protect pharyngeal patency (2). Studies suggest that the degree of anatomical compromise in OSA is highly variable, as is the robustness of the upper airway dilator muscle reflexes. The accumulation of respiratory stimuli during sleep can help to activate the upper airway dilator muscles and thus prevent repetitive pharyngeal collapse (3). One factor thought to be important is the arousal threshold i.e., the propensity to wake up from sleep (4). Some individuals have a low arousal threshold i.e., wake up easily whereas others have a high arousal threshold i.e., hard to wake up. The importance of arousal was discussed extensively at the American Thoracic Society (ATS) 2016 meeting in San Francisco. Several concepts emerged from this meeting and from the recent literature: