Northera Improves Postural Tachycardia Syndrome (POTS) and Postural Vasovagal Syncope (VVS)

Inclusion Criteria: * Both male and female participants are being studied * Ages 18-30 years old * POTS cases will be referred for day-to-day Orthostatic Intolerance (OI) with ≥3 symptoms for \>6 months. * POTS will be confirmed by medical history indicating chronic OI, and by a prior 700 tilt table test or standing test showing excessive tachycardia and symptoms OI in the absence of hypotension. * VVS (fainting) subjects will have at least 2 episodes of postural VVS during the past calendar year. * Healthy volunteers will be included for Study #1 Exclusion Criteria: * Only those free from all systemic illnesses will be eligible to participate. This excludes patients with illnesses associated with autonomic dysfunction such as diabetes, renal disease, congestive heart failure, systemic hypertension, acute and chronic inflammatory diseases, neoplasm, immune mediated disease, trauma, obesity, cancer, supine or upright hypertension, and peripheral vascular disease. * No subjects will be taking neurally active, or vasoactive drugs. Prior medication will be stopped for at least 2 weeks.