Researchers at Charité – Universitätsmedizin, Berlin, have found that Dronabinol, a prescription medicine derived from tetrahydrocannabinol (THC), significantly reduced nightmares in people with post-traumatic stress disorder (PTSD). In the randomised, placebo-controlled trial, published in Nature Medicine, 170 patients were split into two groups, one receiving the THC medicine and the other a placebo, with neither patients nor researchers aware of who had received which until the trial’s end.
PTSD can develop after severe traumatic experiences such as disasters, serious accidents, violence, and combat. Among its most debilitating symptoms are recurrent nightmares, in which patients relive traumatic memories with disorienting intensity, often night after night, leading to chronic sleep deprivation and, in many cases, a conditioned dread of sleep itself. Antidepressants and certain blood-pressure medications are commonly prescribed off-label to manage the symptom, but researchers note their effect on nightmares specifically is often limited. No medication is currently approved in Germany specifically for trauma-related nightmares.
Patients took a single nightly dose of Dronabinol or placebo before bed. Dosing began low and was titrated upward over the first four weeks – a standard precaution given how variably individuals respond to THC – before six weeks at a stable maintenance dose, allowing time for the treatment’s full effect to emerge.
By the end of the trial, nightmare severity, measured on an eight-point scale, had fallen by an average of 3.7 points in the Dronabinol group, compared with 2.2 points among those in the placebo group, a statistically significant difference. More than a third (34.7%) of patients receiving the active treatment reported their nightmares had ceased entirely, and a further one in five (21%) reported the burden had at least halved. Five in six (83%) of the treatment group rated their overall health as markedly improved, against roughly a quarter (24%) on placebo.
“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,” said Stefan Röpke, the psychiatrist who led the research.
Notably, the improvement was specific to nightmares and sleep; the trial found no significant effect on broader PTSD severity or on depression, which frequently co-occurs with the condition. This is consistent with the trial’s design: nightmare frequency was the primary endpoint researchers set out to measure, with wider PTSD symptoms tracked only as secondary outcomes. The result should be read as confirmation that the treatment does the specific job it was designed for, rather than as evidence it fails to do more.
Side effects were generally mild, including dizziness, headache and increased appetite. Researchers reported no serious adverse events attributable to the medication and no withdrawal symptoms following the trial’s conclusion.
The study was conducted across four sites in Germany, including Charité’s St. Hedwig Hospital, the University Medical Center Hamburg-Eppendorf, and the Central Institute of Mental Health in Mannheim, with support from the pharmaceutical company Bionorica SE. Cannabis-based medicines have been more readily prescribable in Germany since the country’s “Cannabis for medical purposes” legislation took effect in 2017, and are already established in pain management where conventional treatments prove insufficient or poorly tolerated.
The findings add to a growing body of evidence supporting cannabis-based treatment for PTSD and related mental health conditions. As leafie previously reported, a UK survey of over 6,000 medical cannabis patients earlier this year found that 97.6% of those treated for anxiety, depression or PTSD reported an improvement in their symptoms, with 92.3% reporting improved sleep specifically.
