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Received — 9 August 2026 ⏭

Study Finds Nightmares Connected to PTSD are Reduced or Completely Eliminated by THC from Cannabis

✇The Debrief
By: Christopher Plain
7 August 2026 at 13:47

Researchers at Charité – Universitätsmedizin Berlin have demonstrated the potential for using THC, the psychoactive component in cannabis, to treat or even eliminate debilitating nightmares associated with post-traumatic stress disorder (PTSD).

The researchers behind the findings said that THC did not reduce other PTSD symptoms, such as the condition’s severity or depression. However, they plan to further explore its ability to treat nightmares, including the potential safety and efficacy associated with long-term use.

PTSD Nightmares Cause Sleep Deprivation and Fear of Going to Sleep

According to a statement from the Charité team, people who survive or witness extreme experiences such as abuse, war, disasters, or other acts of violence can become overwhelmed and unable to consciously process their experience. As a result, many experience what researchers term an “echo,” where the subconscious tries to process the trauma. The more common term for the experience is post-traumatic stress disorder, or PTSD.

People suffering from this condition often report nightmares as one of the most persistent and debilitating symptoms. Along with the horror associated with continuously reliving their traumas, sometimes on a nightly basis, sufferers also experience severe sleep deprivation. These problems are then compounded by a fear of going to sleep and experiencing nightmares repeatedly.

Attempts to treat PTSD related nightmares have found mixed results. For example, some doctors have prescribed antidepressants or blood pressure-lowering medications to treat the symptoms. However, the research team notes that pharmacological treatments are only partially effective, and “often fail to adequately relieve” PTSD-related nightmares.

There is one medication specifically approved for treating PTSD-induced nightmares. However, the team notes, it is not yet widely available, including in Germany where the study was performed. 

Exploring Alternative Treatments

To explore alternative treatment solutions, Prof. Stefan Röpke, who conducts research on trauma-related disorders at the Department of Psychiatry and Neurosciences on the Benjamin Franklin Campus of Charité, and colleagues designed experiments around tetrahydrocannabinol, or THC.

Although widely used for recreational purposes, cannabis has shown some promise for treating a wide variety of medical and psychological conditions. Still, until recently, the drug’s legal status has limited its medical applications, offering researchers a potentially untapped source of PTSD nightmare relief.

For this study, Professor Röpke and colleagues were interested in THC’s established interactions with the human body’s endocannabinoid system. That’s because this system plays a role in sleep regulation, stress, and the processing of emotional memories.

For example, the professor explained, some evidence suggests that THC reduces activity during REM sleep. Known as the dream state, REM sleep is an intense dream phase during which “the brain processes experiences and regulates emotions.

“THC reduces dream activity and thereby alleviates nocturnal stress responses,” the professor explained.

More Than a Third Report Complete Elimination of Nightmares

To start, the team enlisted more than 170 study participants. Critically, all participants suffered from PTSD and intense nightmares, resulting in sleep deprivation and a fear of going to sleep. Instead of smoking cannabis, the researchers administered a form of cannabis-derived THC drops called Dronabinol. As a legal medication, this form of THC is considered clinically safe.

During the ten-week study period, each participant was instructed to take the drops before bedtime. Half of the participants received THC drops, while the others received cannabis-flavored placebo drops. To maintain double-blind study integrity, neither the participants nor the researchers knew who received which treatment.

After the trial period finished, the researchers discovered several positive results. Most notably, the THC group reported a significant decrease in nightmares compared to the placebo group.

According to the study authors, when ranking a participant’s “nightmare burden” on a scale of zero to eight points, participants’ scores dropped by an average of 3.7 points. For comparison, the placebo group experienced an average drop of 2.2 points.

Perhaps even more significant, Professor Röpke said that “more than a third” of the THC patients reported a complete absence of nightmares after the ten-week period concluded. The professor also noted that 21 percent of the study participants reported that their nightmare burden had been at least cut in half. Finally, the professor said that five out of six study participants in the THC group “felt their health had markedly improved.”

Exploring the Safety and Efficacy of Long-Term THC Use

Although the study results offer some possible hope for relief from nightmares and improved sleep, the researchers said the THC treatments did not affect all PTSD symptoms. For example, they observed that a participant’s PTSD severity and any accompanying depression “did not change conclusively.”

No severe side effects were reported by the THC group. However, the researchers did observe some minor complaints, such as headaches, dizziness, or increased appetite. Participants did not report any withdrawal symptoms after the cessation of the treatment period.

Moving forward, the team will explore the safety and effectiveness of long-term nightly THC treatments. They also hope to explore whether patients develop a tolerance to THC’s nightmare-abating effects over time.

The study “Dronabinol for nightmares in post-traumatic stress disorder: a randomized controlled trial” was published in Nature Medicine.

Christopher Plain is a Science Fiction and Fantasy novelist and has spent the last six years as Associate News Editor and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him at christopher@thedebrief.org

'Poop pills' may ease insomnia by reprogramming the gut microbiome, early study hints

✇Live Science
3 August 2026 at 15:10

A poop transplant — otherwise known as a fecal microbiota transplant (FMT) — may help adults with long-term insomnia sleep better, a small study suggests.

After the transplant, study participants' gut bacteria became more diverse than an untreated group of people with insomnia. Their sleep efficiency, meaning the percentage of time they spent asleep while in bed, also increased, researchers reported July 22 in the Journal of Internal Medicine.

If future studies confirm that FMT is safe and effective for the treatment of insomnia, it could become another tool against the sleep disorder, joining sleeping pills and cognitive behavioral therapy (CBT).

The findings "are aligned with a recent body of work over the last five years indicating that the gut microbiome may play a role in sleep-wake regulation," said Dr. David Gozal, a pediatric sleep specialist at Marshall University in West Virginia who wasn't involved in this study.

However, "these results should be regarded as promising proof-of-concept evidence rather than confirmation that FMT is ready for routine treatment of insomnia," Kenji Hashimoto, a forensic mental health researcher at Chiba University in China who wasn't involved with the study, told Live Science in an email.

Improving sleep with "poop pills"

The study included 80 adult women and men with chronic insomnia from seven hospitals in China; the participants did not have other health problems, such as migraine or obstructive sleep apnea, that could interfere with the results.

Half of the participants took antibiotics for two days to clear out some of their existing gut bacteria. Then, they swallowed 60 FMT capsules chockfull of gut bacteria from healthy donors who had been confirmed to be good sleepers. These bacteria were isolated from fecal samples from the donors. Two weeks later, this group took a booster dose of 20 capsules.

The other half of the participants instead took placebo pills in place of the antibiotics and FMT capsules.

The researchers used an overnight sleep assessment called a polysomnography, which records brain waves, eye movements, heart rate, oxygen levels and breathing patterns, to assess the participants. The results showed that sleep efficiency in the FMT group jumped from 79% before the transplant to 93% one month after treatment, on average. The placebo group's sleep efficiency barely changed, shifting from about 85% to 87%.

Additionally, the treated group woke up less throughout the night. Their time spent awake after initially falling asleep fell from 79 to 17 minutes, while the same metric increased from 37 to 42 minutes in the placebo group.

On questionnaires, the FMT group continued reporting better sleep from two all the way to six months after treatment.

It is "encouraging" that FMT treatment seemed to improve sleep not only on objective tests, but also in how the participants themselves rated their insomnia, added Harriët Schellekens, a neuroscientist and microbiome researcher at University College Cork in Ireland, who wasn't involved in the work.

sleeping woman in bed wearing an eye mask

Based on several metrics, the sleep of the treated group improved more than the untreated group in the trial. (Image credit: Kilito Chan via Getty Images)

Gut-sleep connection

The results also suggest that the treatment is safe. In the FMT group, only three out of 40 participants had side effects, and they were mild, such as nausea and transient fever.

However, experts noted several caveats. The trial was small and limited to relatively healthy adults in China, so the results may not apply broadly. Sleep was measured only once after treatment, at the one‑month mark, Hashimoto said. And because the treatment combined antibiotics with FMT, it's unclear how much of the benefit came from the donor microbes alone, Schellekens and Hashimoto noted.

Hashimoto added that the study focused exclusively on the gut microbiota. "Microbial communities in other body sites, particularly the oral and nasal cavities, may also influence sleep regulation through immune, metabolic, and neural pathways and through oral-gut-brain or nasal-gut-brain communication," he said.

The gut and brain communicate in various ways, including via chemicals made by gut microbes that travel to the brain via the bloodstream, Hashimoto explained. These chemicals may steer inflammation, stress responses and the body's sleep-wake control.

Shifts in certain microbes can alter these gut chemicals and gut barrier function in ways that ripple out to the brain and change sleep patterns, Gozal said. Conversely, disrupted sleep can reshape the microbiome. "The question is, what came first?" he said — a disordered microbiome driving insomnia, or insomnia reshaping the microbiome and worsening symptoms.

In the study, the mix of gut microbes in the FMT group shifted between the start and end of the study, but the placebo group's microbiomes stayed the same. Several types of bacteria became more abundant after FMT, while others decreased, suggesting that FMT reshapes the gut microbiome.

Not everyone responded to the treatment, and they mostly differed in what their gut microbiota looked like before FMT, not after. That suggests that a person's initial microbial makeup may help determine how well they respond to the treatment.

Gozal said he would have liked the study to measure the chemicals made by gut microbes before treatment and then show how those same chemicals changed after FMT.

More research is needed to understand the biological mechanisms underlying the improvements, Schellekens said. For now, "FMT remains an experimental approach for insomnia and is not something that should be used outside carefully controlled clinical studies."

The study's researchers did not respond to a request for comment by the time of publication.

This article is for informational purposes only and is not meant to offer medical advice.

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