Dronabinol Reduces Nightmare Frequency by 57% in PTSD Patients in Randomized Crossover Trial

Researchers recruited 36 veterans and civilians meeting DSM-5 PTSD criteria and administered dronabinol or placebo for four weeks each, separated by a two-week washout. Nightmare logs, CAPS-5 scores, and sleep architecture via actigraphy were tracked weekly. The synthetic THC agonist significantly outperformed placebo on nightmare frequency and sleep continuity without increasing next-day sedation.

The result aligns with earlier small trials of nabilone but extends them by using a longer washout and objective sleep measures. It also suggests cannabinoid signaling may dampen amygdala hyperactivity during REM, a mechanism not captured in standard SSRI trials. Public health impact is immediate for the roughly 6% of U.S. adults with PTSD who report frequent nightmares refractory to prazosin.

Key gaps remain: the sample was 78% male and excluded substance-use disorders, limiting generalizability. A multisite phase-3 trial powered for 200 participants with diverse demographics and 12-month follow-up would be required before guideline changes.