1. Unit for Experimental Psychiatry, Division of Sleep and Chronobiology, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
2. Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
3. Harris Miller Miller & Hanson Inc. (HMMH), Anaheim, CA 92805, USA
4. Westat, Rockville, MD 20850, USA
5. Center for Clinical Epidemiology & Biostatistics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA