Earlier research suggested it might reduce dream intensity during REM sleep, raising the possibility that it could lessen trauma-related nightmares. Although the medicine helped nightmares, it did not significantly reduce all PTSD symptoms or depression. The researchers believe better sleep may greatly improve quality of life even if other PTSD symptoms continue. Nevertheless, the relatively short treatment period means researchers still need to examine long-term safety, effectiveness and whether tolerance develops. If future studies confirm these results, dronabinol could fill an important gap in PTSD treatment.