Effects of Experimental Sleep Disturbances on Receptor Function of Study Drug

Inclusion Criteria: * Healthy, 18-48 year olds meeting criteria for Normal Sleep * Sleep phase within 21:00 and 08:00 * Total sleep time \>6.5 and ≤8.5 hours/night; sleep efficiency ≥85% * Non-smokers/nicotine users * Low caffeine users (≤ 2 cups, q.d.). * Life-time history of exposure to opioids, appropriately prescribed for pain. Exclusion Criteria: * BMI \>35 * Lifetime history of chronic pain * Acute pain * Meet clinical criteria for a sleep disorder * Significant central nervous system disease (e.g., lupus, multiple sclerosis) * Cognitive impairment, brain injury or history of closed head injury with loss of consciousness over 3 mins * Other significant medical or psychiatric morbidity within 6 months or lifetime history of bipolar disorder, psychotic disorder, seizure disorder * Use in the last three months of the following: antidepressants, neuroleptics, sedative hypnotics, isoniazid, glucocorticoids, psychostimulants, opioids * Any contraindicated medical condition * Lifetime history of alcohol or substance used disorder * Clinically significant abnormal complete blood count, hepatic, renal or metabolic panel * Positive toxicology screen for opioids or recreational drugs * Pregnant or lactating women * Significant preadmission psychological distress * Embedded metal objects or fragments or electronic devices in the head or body that would present a risk during MRI * Had exposure to ionizing radiation that in combination with the study's estimated radiation exposure…