THC, the cannabis active ingredient, can put an end to trauma-related nightmares

New treatment approach for severe sleep disorders

Charité - Universitätsmedizin Berlin

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Nightmares are among the most agonizing symptoms of post-traumatic stress disorder (PTSD) – a condition that can develop after exposure to severe traumatic experiences, such as disasters, serious accidents, acts of violence, or wartime experiences. Individuals affected relive the events intensely at night, as if they were real, time and time again. This results in extreme sleep deprivation and fear of going to bed. Existing pharmacological treatment approaches often fail to adequately relieve these nightmares. Researchers at Charité – Universitätsmedizin Berlin investigated whether a prescription medication containing THC – one of the active compounds of the cannabis plant – could help. As they report in Nature Medicine*, more than half of the participants responded to treatment, while more than a third experienced a complete disappearance of nightmares.

Drastic or even life-threatening events can have lingering effects, like an echo. This is referred to as post-traumatic stress disorder (PTSD). The brain is unable to process these overwhelming experiences and stores the memories in such a way that they cannot be consciously controlled. They resurface again and again. Also at night, when people with PTSD relive the trauma over and over again until they wake up – usually in a state of panic. Antidepressants or blood pressure-lowering medications are commonly used to provide relief, among other treatments, but these are only partially effective and usually do not help relieving the nightmares. A medication specifically for treating trauma-related nightmares has not yet been approved in Germany.

Prof. Stefan Röpke conducts research on trauma-related disorders at the Department of Psychiatry and Neurosciences on the Benjamin Franklin Campus of Charité. In their search for new treatment approaches and avenues, he and his team, along with other partners, focused on the principal psychoactive compound of the cannabis plant: tetrahydrocannabinol, or THC for short. This active ingredient, also known for its psychoactive effects, interacts with the body’s endocannabinoid system, which is involved in regulating 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.”

A cannabinoid specifically targeting nightmares

Cannabis-based medications are already finding use in pain management, typically when standard treatments prove insufficient or patients cannot tolerate them. In Germany, this has been possible since the so-called “Cannabis for medical purposes” law took effect in 2017. Since then, it has become easier to use plant-derived or synthetically produced cannabinoids for medical and medical-scientific purposes. For their current study the researchers selected a form of THC derived directly from the cannabis plant in the form of drops – the prescription medication Dronabinol. The aim was to determine whether this approach could alleviate nightmares associated with PTSD and whether its use is safe in this context.

More than 170 patients with post-traumatic stress disorder and frequent, intense nightmares participated in the study. For a ten week period, they received either the medication or an identical-looking, cannabis-flavored placebo every evening before bedtime. Neither the healthcare providers nor the participants knew who was receiving which treatment – the gold standard of medical research, a so-called double-blind, placebo-controlled study.

By the end of the study period, nightmares had decreased to a significantly greater extent in the Dronabinol group than in the placebo group. On a scale of zero to eight points, the nightmare burden decreased by an average of 3.7 points, compared to only 2.2 points in the placebo group – a difference that is clearly noticeable to those affected. “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.”

No dependence or severe side effects

According to the studies, the cannabinoid had a specific effect on nightmares and sleep, but not on all PTSD symptoms. Moreover, the severity of the post-traumatic stress disorder and any accompanying depression did not change conclusively. Nevertheless, the majority of participants experienced significant relief, as the tormenting nightly re-experiencing of the traumatic event was interrupted, allowing for restful sleep. Taking the medication did not cause any severe side effects; however, the researchers observed moderate and mild side effects such as dizziness, headache, or increased appetite more frequently. The study team did not observe any withdrawal symptoms after the end of the study period and the discontinuation of the evening doses. In the next steps going forward, the researchers now aim to determine whether taking the cannabinoid is also effective and safe over the long term, or whether a tolerance effect develops over time.

*Roepke S et al. Dronabinol for nightmares in post-traumatic stress disorder: a randomized controlled trial. Nat Med 2026 Aug 05. doi: 10.1038/s41591-026-04546-9

About the study
The research was initiated and led by Charité; researchers from the Psychiatric University Clinic of the Charité at St. Hedwig Hospital, the University Medical Center Hamburg-Eppendorf, and the Central Institute for Mental Health in Mannheim were also involved. The work was supported by the company Bionorica SE

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Journal

Nature Medicine

DOI

10.1038/s41591-026-04546-9 

 

Butterflies worldwide are on the move as the climate warms

Monash‑led research has revealed that one in ten butterfly species globally has shifted its distribution range, with climate change and extreme weather driving nearly 80 per cent of documented movements

Monash University

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Butterfly species, Junonia villida.

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Credit: Dr Shawan Chowdhury

Monash‑led research has revealed that one in ten butterfly species globally has shifted its distribution range, with climate change and extreme weather driving nearly 80 per cent of documented movements.

The study, the largest of its kind, analysed 6,182 range‑shift records for 1,758 species across 105 countries, drawing on English and non‑English scientific literature as well as 68 expert assessments.

Lead author Dr Shawan Chowdhury, head of the Global Change Ecology Lab from Monash University’s School of Biological Sciences, said the findings expose a rapidly changing natural world, and major blind spots in how biodiversity change is monitored.

“We found butterfly species shifting their ranges on every continent where they occur. The scale is astonishing, and it’s happening far beyond the well‑studied regions of Europe and North America,” Dr Chowdhury said.

“Climate change is now a dominant force reshaping where species can survive. For many butterflies, to survive, the only option is to move, often quickly, to track suitable conditions.”

Published in Nature Ecology & Evolution, the study shows 80 per cent of species expanded their ranges, often moving into newly suitable areas as temperatures rise. At the same time, 27 per cent contracted their ranges, and 22 per cent shifted along the elevational gradients, though elevational shifts were rarely documented in the tropics, a major concern given tropical species’ narrow thermal limits.

When the researchers looked at how many species in each country had documented range shifts, five European countries stood out: the Czech Republic, Finland, Luxembourg, Spain and Sweden; each of which has records for more than half of its butterfly species.

Looking only at species known to shift their ranges within that country or elsewhere, 32 countries had documented shifts for at least a quarter of their known butterfly species, and 10 countries for more than half. 

“One of the most striking insights is how much evidence we were missing,” Dr Chowdhury said.

“When we included non‑English studies and expert knowledge, a completely different global picture emerged. Without these sources, we would have dramatically underestimated the global patterns of range shifts, especially overlooking key patterns in the tropics, where 80 per cent of insect species live.”

The research highlights notable geographic gaps: Central Africa, Southeast Asia, New Guinea and the Amazon Basin remain critically under‑represented despite being global biodiversity hotspots.

“These are the regions where species are most vulnerable and where we know the least,” Dr Chowdhury said.

“Tropical butterflies already live close to their upper thermal limits. Even small increases in temperature can push them beyond their limit, especially when land‑use change is breaking up the very habitats butterflies rely on to move and track suitable climates.” 
The authors warn that without equitable, standardised and multilingual biodiversity monitoring, conservation efforts risk being guided by an incomplete and biased evidence base.

“Butterflies are early‑warning indicators and are signaling a warning across the entire planet. If their ranges shift this dramatically, it signals profound changes across ecosystems” Dr Chowdhury said.

“We urgently need coordinated global monitoring, especially in the tropics, to understand what species are doing, where they’re going, and how we can protect them. This is particularly important to meet the Kunming-Montreal Global Biodiversity Framework targets.”

The study shows that climate‑driven redistribution is not a future scenario but a current, accelerating reality, one that demands new conservation strategies capable of responding to species on the move.

Read the research paper: https://doi.org/10.1038/s41559-026-03117-y

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For more experts, news, opinion and analysis, visit Monash News.

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Journal

Nature Ecology & Evolution

DOI

10.1038/s41559-026-03117-y 

Method of Research

Observational study

Subject of Research

Animals

Article Title

Extensive climate-induced range shifts in butterflies across the globe

Article Publication Date

5-Aug-2026

 

Melting sea ice combines with Arctic ocean to make clouds - study

University of Birmingham

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Embargoed copy of the research paper available on request

Scientists have uncovered a previously unknown natural process that dramatically increases the number of cloud-forming particles in the Arctic atmosphere - potentially altering cloud cover, sunlight reflection, and future climate change.

Publishing their findings today (5 Aug) in Nature Geoscience, an international research team led by the University of Birmingham - including partners from China and Spain - reveals the first real-world evidence that, where Arctic sea ice meets open ocean, marine life and sunlight combine to release a chemical mixture that seeds the sky with cloud-forming particles.

A combination of naturally occurring iodine, sulphur and organic compounds are emitted to create new atmospheric particles. Near the ice edge, the researchers watched the number of particles capable of forming cloud droplets rising fifty-fold in a day.

The warming atmosphere of the Arctic causes the ice to melt. This melting ice exposes more of the productive ice edge, which subsequently makes particles. Those particles can change cloud cover, which affects the Earth’s radiation balance.

Backed by funding from the Natural Environment Research Council (NERC), the team gathered the data during an expedition aboard the Royal Research Ship Discovery around Greenland and the Davis Strait in spring and summer 2022.

Co-author Dr James Brean, Assistant Professor in Atmospheric Science at the University of Birmingham, said: “Our findings provide the first real-world validation of a recently identified atmospheric chemistry mechanism involving iodine oxoacids and sulfuric acid. Until now, this process had only been demonstrated in laboratory experiments at the CLOUD chamber at CERN.”

Researchers also identified a new class of atmospheric compounds known as iodine-containing oxygenated organic molecules (I-OOMs), which appear to play an important role in helping newly formed particles grow large enough to influence clouds.

Dr. James Brean added: “These newly identified compounds help small particles grow into larger particles that can seed clouds - we believe this is the first time such molecules have been observed and implies important new pathways for iodine chemistry.”

Researchers discovered that new particles were forming on more than 80% of sunny days, showing that the process is common in this part of the Arctic. Their formation is driven by compounds that are emitted into the air and chemically transformed under sunlight, which include combination of:

• Iodine compounds released from the ocean, sea ice, and coastal areas.
• Dimethylsulfide, from marine plants and algae.
• Organic compounds released naturally from the ocean or land.

Corresponding author Zongbo Shi, Professor of Atmospheric Biogeochemistry at the University of Birmingham, who led the study, said: "Our discovery is important because these new particles can influence clouds, which play a critical role in determining how much heat is retained or reflected. More clouds or thicker clouds in the warming season could potentially accelerate ice melt while cooling down the open ocean.

“The Arctic has warmed more than three times faster than the global average over the past 40 years, making it one of the most sensitive regions on Earth to climate change. Understanding how natural emissions influences clouds is critical for predicting climate changes in this region. Our discovery will help climate models to improve understanding of how climate change is affecting the Arctic and how the region itself influences global climate."

The strongest effects came from the marginal ice zone, the narrow band where open ocean meets melting sea ice and where marine algae are at their most productive. During one event there, the number of cloud-seeding particles rose from roughly 50 to 1,500 per cubic centimetre.

That band is widening as Arctic sea ice retreats. Because the process is missing from current climate models, its influence on the region is not yet accounted for in projections, and the team is now working to build it in.

ENDS
 

For more information or an embargoed copy of the paper, please contact Tony Moran, International Communications Manager  t.moran@bham.ac.uk or +44 (0)7827 832312

‘Arctic cloud condensation nuclei enhanced by iodine, sulfur and organic precursors’ - Mao Du, James Brean, Douglas R. Worsnop, Congbo Song, Yangmei Zhang, Vipul Lal Chandani, Deepchandra Srivastava, David C.S. Beddows, W. Joe F. Acton,  Darrel Baumgardner, Jo Browse, Anna B. Callaghan, Manjula Canagaratna, Yuqing Dai, Peter M. Edwards, Jingkun Jiang, Thomas M. Jordan, James D. Lee, Roberto Sommariva, Harald Stark, Mark D. Tarn, Loren G. Temple, Gavin H. Tilstone, Mingxi Yang, William J. Bloss, Roy M. Harrison, Manuel Dall’Osto, Zongbo Shi is published in Nature Geoscience.

Notes for editors

• The University of Birmingham is ranked amongst the world’s top 100 institutions. Its work brings people from across the world to Birmingham, including researchers, teachers and more than 40,000 students from over 150 countries.
• England’s first civic university, the University of Birmingham is proud to be rooted in one of the most dynamic and diverse cities in the country. A member of the Russell Group and a founding member of the Universitas 21 global network of research universities, the University of Birmingham has been changing the way the world works for more than a century.
• Participating institutions: University of Birmingham, Birmingham, UK; University of Helsinki, Finland; Aerodyne Research, Billerica, USA; Chinese Academy of Meteorological Sciences, Beijing, China; Droplet Measurement Technologies, LLC, Longmont, USA; University of Exeter, UK; University of York, UK; Tsinghua University, Beijing, China;  Plymouth Marine Laboratory, UK; CIRES and CU Boulder, Boulder, USA; University of Leeds, UK; and Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain.  

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Journal

Nature Geoscience

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Arctic cloud condensation nuclei enhanced by iodine, sulfur and organic precursors

Article Publication Date

5-Aug-2026

 

Europe's carbon sinks under pressure: Unprecedented biomass loss in Europe's forests since 2018

Peer-Reviewed Publication

Technical University of Munich (TUM)

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Katja Kowalski and Cornelius Senf

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Credit: Sebastian Kissel / TUM

• First large-scale assessment of biomass loss across Europe's forests
• Unprecedented increase since 2018 driven by storms, drought, and bark beetles
• Particularly severe biomass losses in Central European forests

Using satellite data, researchers at the Technical University of Munich (TUM) have identified an unprecedented loss of aboveground biomass in Europe’s forests since 2018. Forests in Central Europe, which have been heavily affected by drought and bark beetle outbreaks, have been particularly impacted. The study also shows that even small increases in disturbed forest area can release large amounts of carbon into the atmosphere. The findings raise concerns about the European Union's ability to meet its climate goals.

Unlike previous studies that focused solely on changes in tree cover, this study provides the first Europe-wide assessment of changes in forest biomass. To accomplish this, the research team combined satellite data on tree cover change with information on the amount of biomass stored in forests. Their analysis reveals a clear shift: since 2018, biomass losses have increased sharply, leading to substantially greater losses of carbon stored in forests.

This increase in biomass loss coincided with a major rise in bark beetle outbreaks linked to worsening drought conditions. Since 2018, Europe has lost, on average, 46 percent more biomass per year per hectare forest area than during the period from 1985 to 2017. While both timber harvesting and natural disturbances contribute to biomass losses, the researchers attribute the sharp increase since 2018 primarily to climate change-related events. “The changes since 2018 are difficult to explain without climate change. As droughts become more frequent and severe, trees are weakened and bark beetles benefit from increasingly favorable conditions. We expect such events to become more frequent in the future, so they need to be taken into greater account in forest management planning, especially if we intend to rely on Europe’s forests as carbon sinks,” says Katja Kowalski, a researcher at the Professorship of Earth Observation for Ecosystem Management at TUM and lead author of the study.

Hotspots of carbon emissions

The amount of carbon released depends heavily on the region in which forest disturbances occur. Central European forests contain particularly high amounts of biomass, but they are also especially vulnerable to drought, bark beetles, and storms. In Germany, which has the largest standing timber stock in the European Union, disturbed forests release an average of about 125 tons of biomass or roughly 230 tons of CO₂ equivalents per hectare each year. Before 2018, that figure was approximately 170 tons of CO₂ equivalents per hectare. Mediterranean and Scandinavian forests contain less biomass on average due to their ecological characteristics and growing conditions. As a result, disturbances in these forests release less carbon per hectare. In Central Europe, rising disturbance rates thus have particularly severe consequences for the carbon sink capacity of Europe’s forests.

According to the researchers, 18 percent of all biomass losses in Europe between 1985 and 2023 were caused by natural disturbances such as insect outbreaks, storms, and wildfires. Between 1985 and 2017, natural disturbances accounted for 17 percent of biomass losses. From 2018 to 2023, that share had risen to 23 percent.

The much larger share, 82 percent (1985-2023), resulted from forest management activities. “Unlike natural disturbances, we can influence these human interventions,” says Cornelius Senf, Professor of Earth Observation for Ecosystem Management at TUM. “In addition, biomass removed from forests does not usually enter the atmosphere as CO₂ immediately. Instead, it is often used as a raw material for buildings or furniture.” While timber harvesting increased steadily over the study period, the increase was moderate.

Implications for EU climate targets

The researchers also view their findings in the context of European climate policy. The European Union has set a target of increasing annual carbon removals from forests to 310 megatons of CO₂ equivalents by 2030 in order to offset emissions that are difficult to avoid in other sectors. Yet the performance of Europe’s forests as carbon sinks is already declining. According to recent studies, Europe’s forests stored about 72 percent less CO₂ equivalents during 2020-2022 than they did between 2010 and 2014. The TUM study suggests that this trend could become even more pronounced.

To counteract this development, Cornelius Senf advocates for adapted forest management practices: “Forests are certainly capable of recovering from disturbances. There is reason to be optimistic, because most disturbed areas will eventually regain their role as carbon sinks. Our task now is to restore their capacity to store carbon and to adapt forests to future conditions.”

Further Information:

• The research was supported through the European Space Agency’s Climate Change Initiative as part of the RECCAP-2 project, as well as by the EU-funded ForestPaths project. Both projects use satellite data to quantify changes in Europe’s forests and their role as carbon sinks.
• Cornelius Senf is a member of the TUM School of Life Sciences and the Center for Alpine Forest Management at TUM.
• In 2026, he was appointed by NASA and the U.S. Geological Survey (USGS) to the Landsat Science Team, an interdisciplinary group of international experts. For more than 50 years, the Landsat program has provided a continuous record of satellite observations, serving as a foundation for research on climate change, land use, ecosystems, agriculture, and urbanization.

Katja Kowalski and Cornelius Senf

Credit

Sebastian Kissel / TUM

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Journal

Nature Geoscience

DOI

10.1038/s41561-026-02032-y 

Method of Research

Data/statistical analysis

Subject of Research

Not applicable

Article Publication Date

5-Aug-2026