This pilot study in healthy volunteers aims to determine if biological sex has an impact on recovery from dexmedetomidine-induced unconsciousness, and if transcranial magnetic stimulation combined with electroencephalography (TMS-EEG) can be used to measure brain complexity during dexmedetomidine sedation without arousing study participants.

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).