Patients with cervical spinal cord injury demonstrate central sleep disordered breathing manifesting as central sleep apnea or a periodic breathing pattern. Understanding the causes of central sleep apnea may be critically important to understanding upper airway obstruction in susceptible individuals, given the critical role of ventilatory motor output in maintaining upper airway patency as evidenced by upper airway narrowing or occlusion at the nadir of ventilator drive during periodic breathing. This study is likely to identify therapeutic strategies that could be tested in large clinical trials, with the ultimate goal of improving quality of life among patients with cervical SCI who also experience central sleep disordered breathing.