REcovery From DEXmedetomidine-induced Unconsciousness

Inclusion Criteria: * Between the ages of 18 to 65 * Normal body weight and habitus, body mass index (BMI) 18 to 30 kg/m2 * Non-smoker * No history of taking stimulants or substance abuse * For women: either use of hormonal contraception, or \> 45 years old and last menstrual period \> 12 months ago in the absence of any contraceptives. * American Society of Anesthesiologists (ASA) physical status classification 1 (ASA 1) * Fluent in English (sufficient to communicate with the study team and understand the consent form) Exclusion Criteria: * Neurologic: epilepsy or positive history of a seizure, stroke, central disorders of hypersomnolence, neuroimmunological disorder (e.g. multiple sclerosis), Meniere's disease, Parkinson's disease, peripheral neuropathy, no significant visual or hearing impairments, findings in the clinical examination suggesting a neurologic disorder * Psychiatric: history or treatment for an active psychiatric problem (including Attention-Deficit / Hyperactivity Disorder (ADHD) and anxiety disorder) * Cardiovascular: hypertension, symptomatic hypotension or bradycardia, myocardial infarction, coronary artery disease, peripheral vascular disease, dysrhythmias, congestive heart failure, cardiomyopathy, valvular disease, familial history of sudden cardiac death * Respiratory: bronchitis, asthma, chronic obstructive pulmonary disease, smoking, shortness of breath, sleep apnea * Gastrointestinal: esophageal reflux, hiatal hernia, ulcer * Hepatic: hepatitis, jaundice, ascites * Renal: acute or chronic severe renal insufficiency * Reproductive: pregnancy, breast-feeding * Endocrine: diabetes, thyroid disease, adrenal gland disease * Hematologic: blood dyscrasias, anemia, coagulopathies * Musculoskeletal: prior surgery or trauma to head neck or face, arthritis, personal or family history of malignant hyperthermia * Medications: regular use of prescription and non-prescription medications expected to affect central nervous function, anticoagulant or thrombocyte-aggregation inhibiting therapy; exception: oral hormonal contraception * Allergies: dexmedetomidine, phenylephrine, betablockers (including labetalol and esmolol), hydralazine, glycopyrrolate Potential participants will not be enrolled in our study if they fail to pass a standard drug screening test (toxicology).