This trial is testing different medications given before sleep to help patients with obstructive sleep apnea. These patients have weak throat muscles when they fall asleep, causing their airways to collapse. The medications aim to keep these muscles active during sleep to prevent this collapse. Initial findings in a study of 73 adults with moderate or severe OSA reported that the cannabinoid, dronabinol, reduced the number of airway collapse events per hour from 25.9 to 15.2 (2.5 mg dose) and 13.0 (10 mg dose).