1. Sleep-Ventilation Unit, Pneumology Service, Río Hortega University Hospital, Valladolid, Spain
2. Biomedical Engineering Group, University of Valladolid, Valladolid, Spain
3. Unidad Multidisciplinar de Sueño, CIBER Respiratorio, Hospital Universitario de Burgos, Burgos, Spain
4. Section of Sleep Medicine, Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, Illinois