1. Department of Internal Medicine, Section of Pulmonary, Critical Care, and Sleep Medicine, Yale University School of Medicine, New Haven, CT, USA;
2. VA Connecticut Healthcare System, West Haven, CT, USA;
3. Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA;
4. Clinical Neurosciences Division, US Department of Veterans Affairs National Center for Posttraumatic Stress Disorder, West Haven, CT, USA