The investigators will be studying the sedative drug dexmedetomidine using hybrid PET/fMRI/EEG imaging to better understand the neuropharmacology of anesthesia/artificially induced sleep.

A group of healthy volunteers will undergo simultaneous PET/fMRI/EEG imaging under two different conditions: while being administered a sedative (dexmedetomidine), and while being administered a normal saline infusion, as a control. The order of these two scans will be randomized, and the study design is open label (ie subjects and investigators know which session will be the control scan and which one will be the sedative scan). Investigators hope that by comparing the results of the sedative and control scans, the different neuromodulatory states involved in the transition from wakefulness to medically induced vs naturally occurring sleep can be better understood.

Inclusion Criteria:

• Adults aged 18-45.
• No contraindications to MRI or PET scanning.

Exclusion Criteria:

• Contraindications to fMRI scanning and PET scanning (including presence of a cardiac pacemaker or pacemaker wires, metallic particles in the body, vascular clips in the head or previous neurosurgery, prosthetic heart valves, claustrophobia);
• Pregnancy or breast feeding;
• Current or past history of major medical, neurological, or psychiatric condition;
• History of major head trauma;
• Any cardiovascular disorders, including heart disorders or high blood pressure [>155/95];
• Breathing problems such as severe asthma;
• Bleeding disorder, or use of anticoagulants;
• Bladder obstruction, urinary problems, or history of impaired elimination;
• Known kidney or liver problems;
• Intestinal blockage;
• Raynaud syndrome
• Peripheral nerve injury;
• Diabetes;
• Glaucoma;
• Sleep disorder, such as sleep apnea, insomnia, or narcolepsy
• Current use of any drugs that affect sleep
• Current or recent use of medications (neurological or psychiatric) affecting brain function
• Current or past history of chronic pain (assessed at discretion of PI);
• History of allergic reactions
• History of chronic obstructive pulmonary diseases
• Ulcerative skin conditions or other dermatologic conditions which could interfere with blood pressure cuff placement
• Body mass index above 30
• Current smoker
• Lack of current health insurance coverage
• Employed under the direct supervision of the investigators conducting the research
• Hair in dreadlocks, twists, or braids that cannot be removed
• Eczema on the scalp or face