1. Mayo Clinic, Rochester, MN
2. Mount Sinai Medical Center,New York, New York
3. St. Joseph Memorial Hospital, Murphysboro, IL
4. VA Greater Los Angeles Healthcare System-Sepulveda and University of California, Los Angeles, CA
5. University of North Carolina, Chapel Hill, NC
6. Louisiana State University, Shreveport, LA
7. Stanford University, Stanford, CA
8. University of Washington, Seattle, WA
9. Barrow Neurological Institute, Phoenix, AZ
10. Rhode Island Hospital Providence, RI
11. Toronto, Canada
12. Houston Sleep Center,Houston, TX