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 lastmenstrual 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 theconsent form)

Exclusion Criteria:

• Neurologic: epilepsy or positive history of a seizure, stroke, central disorders ofhypersomnolence, neuroimmunological disorder (e.g. multiple sclerosis), Meniere'sdisease, Parkinson's disease, peripheral neuropathy, no significant visual orhearing impairments, findings in the clinical examination suggesting a neurologicdisorder

• Psychiatric: history or treatment for an active psychiatric problem (includingAttention-Deficit / Hyperactivity Disorder (ADHD) and anxiety disorder)

• Cardiovascular: hypertension, symptomatic hypotension or bradycardia, myocardialinfarction, coronary artery disease, peripheral vascular disease, dysrhythmias,congestive heart failure, cardiomyopathy, valvular disease, familial history ofsudden 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, personalor family history of malignant hyperthermia

• Medications: regular use of prescription and non-prescription medications expectedto affect central nervous function, anticoagulant or thrombocyte-aggregationinhibiting therapy; exception: oral hormonal contraception

• Allergies: dexmedetomidine, phenylephrine, betablockers (including labetalol andesmolol), hydralazine, glycopyrrolate

Potential participants will not be enrolled in our study if they fail to pass a standard drug screening test (toxicology).