1. Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, and Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
2. Institute of Human Movement Sciences and Sports, Swiss Federal Institute of Technology, Zurich, Switzerland.
3. Medical Intensive Care Unit, University Hospital of Zurich, and Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.