1. Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Division of Sleep Medicine, Harvard Medical School, Boston, MA
2. Stanford University Sleep Clinic and Center for Human Sleep Research, Redwood City, CA
3. Sleep Medicine and Research Center, St. Luke's Hospital, Chesterfield, MO
4. Providence St. Mary Medical Center, Walla Walla, Washington
5. VA Boston Healthcare System, Boston, MA
6. Arizona Respiratory Center, University of Arizona, Tucson, AZ