1. Sleep Disorders Center, Walter Reed National Military Medical Center, Bethesda, Maryland
2. Uniformed Services University of the Health Sciences, Bethesda, Maryland
3. Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
4. Sleep Disorders Center, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
5. Walter Reed Army Institute of Research, Silver Spring, Maryland