Predictors of Response to a Nasal Expiratory Resistor Device and Its Potential Mechanisms of Action for Treatment of Obstructive Sleep Apnea Predictors of Response to a Nasal Expiratory Resistor Device and Its Potential Mechanisms of Action for Treatment of Obstructive Sleep Apnea Download Vitamin D, Race, and Excessive Daytime Sleepiness A Case a Week: Sleep Disorders from the Cleveland Clinic