Nightmares are a painful part of post‑traumatic stress disorder (PTSD). When a person with PTSD sleeps, the brain can replay the scary event over and over, making it hard to rest. Traditional medicines often do not stop these vivid dreams.
Scientists at Charité – Universitätsmedizin Berlin tested a prescription drug that contains THC, the main psychoactive ingredient in cannabis. The drug is called dronabinol and is taken as drops before bedtime. Their results, published in Nature Medicine, show that more than half of the participants felt better, and over a third said their nightmares vanished completely.
Why PTSD Nightmares Are Hard to Treat
After a traumatic event, the brain can store memories in a way that makes them pop up without warning. This can happen during the day and at night. While sleeping, many people with PTSD wake up in panic because they relive the trauma. Antidepressants and blood‑pressure medicines are sometimes used, but they rarely calm the nightmares themselves. In Germany, no drug is officially approved for trauma‑related dreams.
How THC Might Help
THC works with the body’s endocannabinoid system, which helps control sleep, stress, and emotional memory. Professor Stefan Röpke, who studies trauma disorders, explains that during REM sleep – the stage when we dream – THC can lower dream activity. This calming effect may reduce the stress response that fuels night‑time terror.
The Dronabinol Trial
Since cannabinoids are already used for pain when other treatments fail, researchers wanted to see if dronabinol could also help with PTSD nightmares. After Germany passed a law in 2017 to allow medical cannabis, they recruited more than 170 adults who suffered from frequent, severe nightmares.
For ten weeks, participants received either dronabinol drops or a placebo that tasted like cannabis but contained no THC. The study was double‑blind, meaning neither the participants nor the doctors knew who got the real medicine.
Results: Fewer and Weaker Nightmares
At the end of the study, the dronabinol group showed a much larger drop in nightmare intensity. On a scale of 0‑8, their average score fell by 3.7 points, while the placebo group improved by only 2.2 points.
More than one‑third of the dronabinol users reported that they no longer had any nightmares after ten weeks. Another 21 % said their nightmare burden was cut in half. Overall, about five out of six participants felt a noticeable boost in their health.
Safety and Side Effects
The medication mainly affected sleep and dreams, without a clear impact on other PTSD symptoms such as anxiety or depression. No severe side effects were observed. Some people experienced mild dizziness, headaches, or a greater appetite, but these were not serious.
Importantly, participants did not develop withdrawal symptoms after stopping the drops, suggesting a low risk of dependence.
What Comes Next?
Future research will test whether dronabinol remains safe and effective over longer periods and whether patients might build tolerance to its effects. The study was led by Charité with support from other German research hospitals and the company Bionorica SE.