A new approach to treating severe sleep disorders.
For many people with post-traumatic stress disorder (PTSD), going to sleep can mean reliving a traumatic experience with frightening intensity. These recurring nightmares can cause severe sleep loss and even create fear of going to bed, while existing medications often provide limited relief. Researchers at Charité – Universitätsmedizin Berlin have now tested whether Dronabinol, a prescription medication containing tetrahydrocannabinol (THC), could reduce these nighttime symptoms. In results reported in Nature Medicine, more than half of participants responded to treatment, and more than one third said their nightmares disappeared completely.
PTSD can develop after experiences such as disasters, serious accidents, acts of violence, or wartime events. Traumatic memories can repeatedly return beyond conscious control, including during sleep, when people may experience the event again until they wake, often in panic. Antidepressants and blood pressure-lowering medications are among the treatments currently used, but their effects can be incomplete and they generally provide limited relief from nightmares. No medication specifically for trauma-related nightmares has been approved in Germany.
THC targets sleep and emotional processing
Prof. Stefan Röpke, who studies trauma-related disorders at the Department of Psychiatry and Neurosciences on Charité’s Benjamin Franklin Campus, and his collaborators turned to THC, the main psychoactive compound in cannabis. THC interacts with the endocannabinoid system, which helps regulate sleep, stress, and the processing of emotional memories.
Stefan Röpke explains: “There is evidence suggesting that during REM sleep—the intense dream phases in which the brain processes experiences and regulates emotions—THC reduces dream activity and thereby alleviates nocturnal stress responses.”
Cannabis-based medicines are already used in pain treatment, particularly when conventional therapies are ineffective or poorly tolerated. Germany expanded access to plant-derived and synthetic cannabinoids for medical and medical-scientific purposes after its “Cannabis for medical purposes” law took effect in 2017. For this study, Röpke and his collaborators chose Dronabinol, a prescription form of THC derived directly from cannabis and administered as drops, to test whether it could safely reduce PTSD-related nightmares.
A controlled trial tests Dronabinol
More than 170 people with PTSD who experienced frequent, severe nightmares joined the trial. For ten weeks, participants took either Dronabinol or an identical-looking, cannabis-flavored placebo each evening before going to sleep. Neither the participants nor the healthcare providers knew who received the medication, making the trial double-blind and placebo-controlled.
Nightmare symptoms declined significantly more among people taking Dronabinol. On an eight-point scale, average nightmare burden fell by 3.7 points in the treatment group, compared with 2.2 points among participants receiving placebo.
“More than a third of the patients treated with Dronabinol reported that they no longer experienced any nightmares after ten weeks. Another 21 percent reported that their nightmare burden had been at least halved,” as Stefan Röpke stated. “And about five out of six patients in the dronabinol group felt their health had markedly improved.”
Benefits were specific, with caveats
The cannabinoid appeared to have a targeted effect on nightmares and sleep rather than on PTSD as a whole. The researchers could not conclusively show changes in overall PTSD severity or accompanying depression. Even so, many participants experienced relief when repeated nighttime re-experiencing of traumatic events was interrupted, allowing more restful sleep.
No severe side effects were reported, although mild and moderate effects such as dizziness, headache, and increased appetite occurred more frequently with Dronabinol. The researchers also observed no withdrawal symptoms after participants stopped the evening medication at the end of the study.
The next question is whether those benefits can persist. Röpke and his collaborators plan to investigate whether Dronabinol remains effective and safe with longer use, and whether patients eventually develop tolerance that reduces its effects.
Reference: “Dronabinol for nightmares in post-traumatic stress disorder: a randomized controlled trial” by Stefan Roepke, Nikola Schoofs, Kathlen Priebe, Felix Wuelfing, Kristina Meyer, Astrid Gieselmann, Katharina Stieglbauer, Milagros Galve, Sarah Biedermann, Jürgen Gallinat, Ingo Schäfer, Christian Schmahl, Jenny Zähringer, Robert Roehle, Erin D. Sprünken, Tim Friede, Stefan M. Gold, Tolou Maslahati, Christian Otte and Stefanie Koglin, 5 August 2026, Nature Medicine.
DOI: 10.1038/s41591-026-04546-9
This was an investigator-initiated trial supported by an unrestricted grant from Bionorica SE, which also provided the study medication.
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