Influence of Osmotic Stimulation of Vasopressin on Autonomic Function

Inclusion Criteria: * Males and Females between the ages of 18 - 35 Exclusion Criteria: * 1\) evidence of clinically relevant diseases that may alter body water regulation (e.g., diabetes, kidney disease, metabolic disorders, cardiovascular disease, and other potential fluid balance covariates such as habitual use of non-steroidal anti-inflammatory drugs or serotonin reuptake inhibitors, 2\) previous surgery on the digestive tract that may impair the body's ability to normally regulate body water, 3\) regular drug treatment within the previous 15 days, 4\) actively attempting to gain or lose body weight, 5\) For female participants, testing will take place during the early follicular phase of their menstrual cycle (days 1-8) to maintain consistency in the hydration status measures as total body water fluctuates over the course of the menstrual cycle. Females who are currently using contraceptives (e.g., IUD) that limit the number of menstrual cycles occurring in a given year will be excluded from this study to ensure accuracy in the testing periods for this study.