These repeated episodes can cause severe sleep loss and make some people afraid to go to bed. Why PTSD Nightmares Are So Difficult to TreatThe effects of a terrifying or life-threatening experience can continue long after the immediate danger has passed. THC interacts with the body's endocannabinoid system, which helps regulate sleep, stress, and the way emotional memories are processed. For the study, the researchers used Dronabinol, a prescription medication containing THC obtained directly from the cannabis plant and administered as drops. More than 170 people with post-traumatic stress disorder and frequent, severe nightmares took part.