1. Department of Anesthesiology, Uniformed Services University of the Health Sciences, Bethesda, Maryland
2. Department of Sleep Medicine, Walter Reed National Military Medical Center, Bethesda, Maryland
3. Department of Anesthesiology, Walter Reed National Military Medical Center, Bethesda, Maryland
4. Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, Maryland