1. Sleep Unit, Pneumology Service, University Hospital of Guadalajara, Guadalajara, Spain.
2. Sleep Research Institute, Madrid, Spain.
3. Pneumology Service, Hospital Universitario La Paz, IdiPAZ, Madrid, Spain.
4. Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain.
5. Department of Medicine and Specialties, University of Alcalá, Madrid, Spain.