Subjects categorized as frequent cannabis users (>3x/week for 3 months) will receive a single dose of 10-60mg dronabinol on the second or third night of their stay in the clinical laboratory, one hour prior to bedtime and five minutes after completion of a study snack. The other night, participants will receive a placebo.

Dronabinol is an orally active, synthetic THC currently indicated for weight loss in patients with acquired immune deficiency syndrome (AIDS) or anorexia and for nausea and vomiting associated with cancer. Dronabinol is nearly absorbed (90%-95%) after a single oral dose of the capsule formulation with 10-20% of the administered dose researching the systemic circulation due to extensive first-pass hepatic metabolism and high lipid solubility. The onset of action is ~30 to 60 minutes with peak effects from 2-4-h following dose (Fig. 2) (34). The 10-60mg of dronabinol will be administered by OHSU's research pharmacy services.

Non-cannabis users (who have not used cannabis more than 10 times in their lifetime) will undergo the same single dose dronabinol and placebo as the frequent cannabis user arm, under the identical study procedure.

Single dose oral administration of 10-60mg dronabinol prior to night 2 or 3 sleep in the clinical laboratory.

Polysomnographic recordings will be measured and scored across the three sleep periods for timing and sleep stages.

Psychomotor vigilance response times (in milliseconds) will be measured shortly after awakening each test morning.

Processing speed and working memory (response accuracy) will be measured shortly after awakening each test morning. Scores can range from a minimum of 0 to 60 correct responses with each test.

Verbal memory will be measured shortly after awakening each test morning. Scores can range from recalling 0 words to the complete list. Participants are blinded as to list length.

Assessed by visual analog scale (Minimum=0, Maximum=100). 0 is "Not at all" and 100 is "Extremely". Questions ask about feeling drug effect, high right now, and wanting more of the study drug.

Blood pressure (BP) will be measured every 30 min during wake and every 15 minutes during sleep. Beat-by-beat (BP) will be measured during sleep using a non-invasive device employing the volume-clamp method with hydrostatic correction (BMeye Nexfin or AD Instruments NIBP). Additionally an automated calibrated sphygmomanometer will be used to record sporadic BP at intervals during an exercise challenge.

Subjective sleepiness and alertness will be measured regularly (~1/h) across wake periods during the study protocol using the Stanford Sleepiness Scale. The scale measures subjective sleepiness on a 1-5 point Likert scale with 5 indicating the highest degree of sleepiness and 1 indicating the lowest degree of sleepiness.