Summary: Researchers evaluated dronabinol, a plant-derived Δ9‑tetrahydrocannabinol (THC) formulation, for treating trauma-related nightmares in people with post-traumatic stress disorder (PTSD). The randomized, double-blind, placebo-controlled trial found a statistically significant reduction in nightmare burden for patients receiving dronabinol versus placebo. By week ten, more than one third of patients on dronabinol reported complete resolution of nightmares, and another 21% achieved at least a 50% reduction in nightmare severity.
Dronabinol specifically reduced nocturnal re-experiencing of trauma without producing severe adverse events, withdrawal symptoms, or evidence of dependence in the study timeframe. Mild-to-moderate side effects—most commonly dizziness, headache, and increased appetite—were observed more frequently with dronabinol than with placebo.
Key Facts
- Quantifiable reduction in nightmares: On an 8‑point clinician-rated scale (CAPS‑IV B2), average nightmare burden fell by 3.7 points in the dronabinol group versus 2.2 points with placebo.
- High rate of complete remission: Over 33% of participants receiving nightly dronabinol reported no further trauma-related nightmares after ten weeks of treatment.
- Substantial clinical benefit for many: An additional 21% of dronabinol-treated patients experienced at least a 50% reduction in nightmare severity; approximately five out of six reported marked overall health improvement.
- Symptom specificity: The primary therapeutic effect was on nightmare frequency and sleep disruption. Overall PTSD severity and accompanying depressive symptoms did not show consistent, significant change as secondary outcomes.
- Safety and tolerability: No severe dependence or withdrawal syndrome was detected after discontinuation in this ten-week trial. Adverse events were mostly mild to moderate, including dizziness, headache, and increased appetite.
Source: Charité
Background: Severe or life‑threatening events can leave persistent, intrusive memories and re-experiencing symptoms that are characteristic of post-traumatic stress disorder. For many people with PTSD, these memories emerge repeatedly at night as vivid nightmares that wake them in panic and prevent restorative sleep.
Conventional treatments—such as antidepressants or some antihypertensive agents—can help daytime symptoms or reduce sympathetic overactivity but often fail to reliably relieve trauma-related nightmares. No medication has been specifically approved in Germany for treating PTSD nightmares.
Researchers led by Prof. Stefan Röpke at the Department of Psychiatry and Neurosciences, Benjamin Franklin Campus, Charité, investigated whether the primary psychoactive component of cannabis, THC, could safely and effectively reduce nightmare severity. THC acts on the endocannabinoid system, a regulatory network involved in sleep architecture, stress responses, and emotional memory processing.
Röpke notes that evidence suggests THC may dampen dream intensity during REM sleep—the sleep phase when emotional memories are processed—potentially interrupting nocturnal re‑experiencing and reducing nightmare-triggered anxiety.
Study design and participants: The trial enrolled 171 adults with PTSD and frequent, intense nightmares. Participants were randomized to receive either dronabinol drops (2.5–15 mg nightly, titrated for effect) or a matched cannabis‑flavored placebo for ten weeks. The study was double-blind: neither participants nor clinicians knew treatment assignments.
The primary outcome measured change from baseline to week 10 on the Clinician‑Administered PTSD Scale for DSM‑IV (CAPS‑IV) B2 item, which assesses nightmare frequency and intensity. By week 10, the reduction in CAPS‑IV B2 scores was significantly greater with dronabinol than with placebo (between‑group difference −1.50; 95% CI −2.28 to −0.71; Cohen’s d = 0.65; P < 0.001).
Clinical outcomes and safety: At study end, many participants experienced meaningful relief from nightly trauma re‑experiencing, enabling more restful sleep. Adverse events were reported more often in the dronabinol arm (78 patients, 89.7%) than in placebo (64 patients, 77.1%). Treatment discontinuation due to adverse events occurred in 5.7% of dronabinol patients and 7.2% of placebo patients. Serious adverse events were recorded in seven patients (8.0%) receiving dronabinol and none in the placebo group. No withdrawal symptoms were observed after stopping the nightly doses at the end of the trial period.
The authors conclude that dronabinol reduces the frequency and intensity of PTSD‑related nightmares in the short term, though longer follow‑up is required to determine sustained efficacy, long‑term safety, and whether tolerance develops with extended use.
Funding: The trial was initiated and led by Charité, with contributions from the Psychiatric University Clinic of the Charité at St. Hedwig Hospital, University Medical Center Hamburg‑Eppendorf, and the Central Institute for Mental Health in Mannheim. The research received support from Bionorica SE.
Key Questions Answered:
A: Many standard treatments target daytime mood, generalized anxiety, or peripheral sympathetic activity rather than the neural processes that drive REM sleep dream intensity and emotional memory reconsolidation. They do not directly modulate endocannabinoid‑regulated circuits that influence nocturnal re‑experiencing.
A: THC interacts with cannabinoid receptors involved in sleep and emotional memory processing. During REM sleep, THC appears to reduce dream activity and calm overactive limbic responses, which can prevent the nightly surge of fear and distress that produces traumatic nightmares.
A: In this ten‑week trial, no withdrawal symptoms were documented after discontinuing nightly dronabinol. The results suggest short‑term safety without evidence of addiction within the study period; however, long‑term studies are needed to evaluate tolerance, dependence risk, and sustained safety.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full by editorial staff.
- Additional contextual information was added by the newsroom team.
About this psychopharmacology and PTSD research news
Author: Markus Heggen
Source: Charité
Contact: Markus Heggen – Charité
Image: Image credit: Neuroscience News
Original Research: Open access. “Dronabinol for nightmares in post‑traumatic stress disorder: a randomized controlled trial” by Stefan Roepke et al., published in Nature Medicine. DOI: 10.1038/s41591-026-04546-9.
Abstract
Dronabinol for nightmares in post‑traumatic stress disorder: a randomized controlled trial
Nightmares are a central and disabling feature of PTSD, yet targeted pharmacological options are limited. This multicenter, double‑blind, randomized, placebo‑controlled trial assessed the efficacy and safety of dronabinol (BX‑1; Δ9‑THC) for PTSD‑related nightmares.
Adults with PTSD and recurrent nightmares were randomized to nightly dronabinol (2.5–15 mg) or placebo for 10 weeks. The primary endpoint was the change from baseline to week 10 on the CAPS‑IV B2 item, measuring nightmare frequency and intensity.
A total of 171 patients were randomized (mean age 37.9 ± 12.8 years; 79.3% female): 87 to dronabinol and 84 to placebo. At week 10, CAPS‑IV B2 reductions were significantly greater with dronabinol than placebo (between‑group difference −1.50; 95% CI −2.28 to −0.71; Cohen’s d = 0.65; P < 0.001).
Adverse events were reported by 78 patients (89.7%) receiving dronabinol and 64 (77.1%) receiving placebo. Treatment discontinuation due to adverse events occurred in five (5.7%) and six (7.2%) patients, respectively. Serious adverse events occurred in seven patients (8.0%) receiving dronabinol and in none receiving placebo.
These results provide evidence that dronabinol reduces the frequency and intensity of PTSD‑related nightmares; further research is required to assess long‑term efficacy and safety.
ClinicalTrials.gov: NCT04448808.