The following blood draw procedures will be performed for all participants on Day 1: At 4pm on Day 1, an intravenous line (IV; needle inserted into a vein) will be placed in your arm to draw hourly blood samples used for the measure of adrenocorticotropin (ACTH) and cortisol. ACTH is a hormone that controls the release of cortisol (a stress hormone) in your system and both of these hormones levels change under stressful conditions. The blood samples are taken in small amounts (approximately 1/2 teaspoon) and will be collected at 2pm and 4pm on Baseline Day 1, and then on the hour, every hour, starting at 6pm and ending at 9am the next day. A total of 72 ml(approximately 5 tablespoons) of blood will be drawn. The IV line will be removed following the last blood draw. If you presently live in a time zone different from the Pacific Standard Time zone (for example, Eastern Standard Time zone), we may begin taking hourly blood samples as early as 3pm on Baseline Day 1 in order to more accurately measure your body's daily rhythm of hormones.