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Nightmares can be one of the most distressing symptoms of post-traumatic stress disorder (PTSD), a condition that may develop after a person experiences a disaster, serious accident, violence, combat, or another severe trauma. During sleep, people with PTSD may feel as though they are living through the event again in vivid detail. These repeated episodes can cause severe sleep loss and make some people afraid to go to bed.

Available medications often provide limited relief from trauma-related nightmares. Researchers at Charité — Universitätsmedizin Berlin therefore examined whether a prescription drug containing THC, one of the active compounds found in cannabis, could help. The findings, published in Nature Medicine, showed that more than half of the participants responded to the treatment. More than one-third said their nightmares disappeared completely.

Why PTSD Nightmares Are So Difficult to Treat

The effects of a terrifying or life-threatening experience can continue long after the immediate danger has passed. In post-traumatic stress disorder (PTSD), the brain has difficulty processing overwhelming events. The memories may be stored in a way that makes them return involuntarily and without conscious control.

This can happen during the day and at night. While sleeping, people with PTSD may repeatedly relive the trauma until they wake in panic. Antidepressants and medications that lower blood pressure are among the treatments sometimes used, but their effectiveness is limited. They also often do little to relieve the nightmares themselves. Germany has not yet approved a medication specifically for trauma-related nightmares.

Prof. Stefan Röpke studies trauma-related disorders at the Department of Psychiatry and Neurosciences on the Benjamin Franklin Campus of Charité. While exploring possible new treatments, he and his team, working with additional research partners, turned their attention to tetrahydrocannabinol, commonly known as THC. It is the primary psychoactive compound in cannabis.

THC interacts with the body’s endocannabinoid system, which helps regulate sleep, stress, and the way emotional memories are processed. 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.”

Testing Dronabinol for PTSD Nightmares

Cannabis-based medicines are already used in pain treatment, especially when standard therapies do not work well enough or cause intolerable side effects. In Germany, access became easier after the so-called “Cannabis for medical purposes” law went into effect in 2017. The legislation expanded the medical and scientific use of cannabinoids derived from plants or produced synthetically.

For the study, the researchers used Dronabinol, a prescription medication containing THC obtained directly from the cannabis plant and administered as drops. They wanted to find out whether the drug could safely reduce nightmares linked to PTSD.

More than 170 people with post-traumatic stress disorder and frequent, severe nightmares took part. For ten weeks, participants received either Dronabinol or a cannabis-flavored placebo that looked identical. They took the drops each evening before going to bed.

Neither the participants nor the healthcare professionals knew who received the medication and who received the placebo. This double-blind, placebo-controlled design is considered the gold standard for testing medical treatments.

Nightmares Declined More With THC Treatment

At the end of the ten weeks, nightmare severity had fallen significantly more in the Dronabinol group than in the placebo group. On a scale ranging from zero to eight, the average nightmare burden dropped by 3.7 points among participants taking Dronabinol. The placebo group experienced an average decrease of 2.2 points. For the people affected, the difference was clearly noticeable.

“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 Severe Side Effects or Signs of Dependence

The cannabinoid appeared to act specifically on nightmares and sleep rather than on every aspect of PTSD. The researchers could not conclusively show that it reduced the overall severity of post-traumatic stress disorder or any accompanying depression.

Even so, most participants experienced meaningful relief. By interrupting the repeated nighttime reliving of trauma, the treatment allowed many of them to sleep more peacefully.

No severe side effects were reported. Mild and moderate effects, including dizziness, headaches, and increased appetite, occurred more frequently among those receiving Dronabinol. The researchers also found no withdrawal symptoms after participants stopped taking the evening doses at the end of the study.

Future studies will examine whether the treatment remains safe and effective when used for longer periods. Researchers also want to determine whether patients may gradually develop tolerance to the drug.

Northwestern scientists have identified, for the first time, a specific group of neurons — cells in the brain — that appear to contribute to anxiety caused by cannabinoid drugs, particularly when those drugs are combined with stressful conditions. Cannabinoids are a category of substances that includes THC, the main psychoactive ingredient in cannabis.

To investigate how cannabinoids influence fear and anxiety, researchers exposed mice to a threatening smell derived from fox urine. Before encountering the odor, the animals were given either a placebo or a synthetic cannabinoid drug.

Mice that received the cannabinoid froze more frequently and spent less time exploring the predator scent. Researchers traced these anxiety related behaviors to increased activity in a small population of brain cells known as somatostatin neurons. These neurons are located in the central amygdala, an area of the brain involved in processing fear and stress.

When the researchers genetically silenced the somatostatin neurons, the mice that received the cannabinoid became less likely to avoid the predator odor. The result suggested that these cells play an important role in producing the anxious response.

“The results of this study could explain why a good trip can turn bad pretty quickly if people consume too much cannabis or the situation they are in turns stressful or scary,” said study senior author Dr. Sachin Patel, chair of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine.

The study was published on Oct. 2 in Nature Communications.

Tracking the Brain During a Threat

Patel and his colleagues gave mice several different doses of the synthetic cannabinoid and measured their reactions to the predator odor. The researchers recorded how much time the animals spent near the scent and whether they responded by freezing or fleeing.

At the same time, the team monitored activity inside the brain by implanting a small microscope into the mice’s brain.

Researchers also studied brain tissue to determine how cannabinoids changed communication between neurons. Their experiments showed that the drug weakened a natural brain mechanism that normally acts as a “brake” on somatostatin neurons. With that restraint reduced, the neurons became more active.

“Higher doses of cannabinoids and environmental stress worked together to synergistically release the ‘brake’ on the central amygdala, which in turn drove excessive anxiety,” Patel explained.

Why Cannabis and Anxiety Matter

Cannabis use in the U.S. has steadily increased in recent years. At the same time, emergency department visits involving adverse effects from the drug have also risen.

Previous studies have found an association between cannabis use and a higher long term risk of anxiety. Anxiety and mood disorders are also on the rise globally.

“Understanding how cannabis affects brain function to generate its psychoactive effects could ultimately reveal new ways to counteract negative consequences should they arise in some people,” Patel said.

The researchers believe the findings may also have relevance beyond cannabis related side effects. Patel said the same neurons could potentially represent a broader target for understanding or reducing anxiety.

“Suppressing the activity of somatostatin neurons in the central amygdala could represent a final pathway for reducing anxiety symptoms, not just in the context of cannabis side effects,” he explained.

Most of the brain’s roughly 100 billion neurons are produced before birth. However, the small number of new neurons that continue to form in the adult hippocampus may play an important role in protecting against depression, according to new research from Columbia University Vagelos College of Physicians and Surgeons.

The findings provide the first evidence that neurogenesis, the process of producing new neurons, stalls in the brains of adults with major depressive disorder. Researchers also identified molecular programs involved in controlling this process, offering potential clues for developing new treatments.

“Historically, depression was thought to be a disease of neurotransmitter deficiency, especially serotonin, but we now think that depression stems from multiple issues that affect our neurons’ ability to adapt to stress and changing environments,” says Maura Dupont, professor of psychiatry, who led the research.

“Without the ability to create new neurons, people with depression may not have the resilience to effectively adapt to the environment.”

How New Neurons May Shape Memory and Emotion

The researchers focused on the hippocampus, a brain region that plays a major role in episodic memory and emotional responses to the environment. It is also one of the few areas of the adult brain that continues to generate new neurons.

Although the hippocampus is not the only brain region involved in depression, its influence over both memory and emotion has made it an important area of study. Researchers believe changes there may contribute to the tendency of people with depression to interpret experiences more negatively.

“The hippocampus is important for our ability to distinguish between similar but different memories and separate the emotional connotation of past memories and current events,” Dupont says.

This ability is known as pattern separation. When it becomes impaired, individual memories and the emotions attached to them may become less distinct, allowing separate experiences to blend together.

“You may be out with a friend for lunch, but she’s tired and doesn’t talk much. With intact pattern separation, you remember this as a unique event. With impaired pattern separation, it becomes mixed with previous memories of feeling rejected, leading you to think, ‘They’re upset with me’,” Dupont explains. “And I see this a lot in my patients, where they can only retrieve negative information from their memories.”

Research in mice has shown that adult neurogenesis is necessary for pattern separation. A recent study involving patients with brain tumors, in whom neurogenesis was eliminated by radiation therapy directed at the hippocampus, suggests that the same relationship may exist in humans.

“It’s important to emphasize that we do not yet know the complete mechanism, particularly in humans, but the newborn neurons seem to enhance pattern separation because they are especially responsive to new experiences and can be incorporated into new memory circuits more easily, allowing new memories to be stored separately from the old ones,” Dupont says. “Turning neurogenesis back on may be a way to treat depression in some people by rewiring their hippocampus circuit.”

Depression Affects More Than New Neuron Growth

The researchers found that the changes linked to depression extended well beyond neurogenesis. New neuron formation operates within a larger hippocampal circuit that stores episodic memories along with their emotional significance, and molecular disruptions appeared throughout that system.

The affected genes included those involved in building new connections between neurons, supporting communication among brain cells, supplying cellular energy, and moving materials within cells.

The trisynaptic circuit, the hippocampus’s primary pathway for establishing new emotional memories, also displayed evidence of inflammation and cellular stress in people with depression.

To identify these changes, researchers studied nearly half a million brain cells collected from people with depression and control subjects shortly after each donor’s death.

Using an array of recently developed techniques, the team measured the activity of every gene within individual cells and examined whether cellular proteins had been altered. This enormous dataset allowed researchers to see what individual cells were doing and determine exactly where affected cells were located within the hippocampal circuit.

Genes, Environment, and the Biology of Depression

The analysis revealed altered activity in several genes whose genetic variants have previously been associated with major depression.

Other disrupted genes showed epigenetic changes that may reflect the influence of environmental factors. Epigenetic mechanisms can adjust how strongly genes are turned on or off without altering the underlying DNA sequence.

“These are like dimmer switches that control how active genes are, and they are affected by life experiences such as stress, learning, aging, chemicals, etc.,” Dupont says.

The diversity of molecular changes may also help explain why depression can look so different from one person to another.

“Overall, the wide range of effects we found could reflect different pathogenetic mechanisms, perhaps indicating that depression is not just one disease,” she adds.

Researchers still have only a limited understanding of depression’s underlying biology, according to Dupont. By defining the disorder more precisely at the cellular and molecular levels, studies like this one could eventually provide new targets for treatment.

Toward Molecular Subtypes of Depression

Dupont and her colleagues hope that depression could eventually be classified according to its molecular characteristics, much as cancer increasingly is today.

“We want to reclassify depression based on its molecular features, similar to what has been done in cancer,” Dupont says. “Classifying cancers based on their cellular characteristics, not their locations, has led to new and improved treatments. We hope the same will be true for depression and other psychiatric or brain diseases.”

Researchers led by the University of Texas at Austin have created a soft wearable patch that improved REM sleep in real-world testing without medication or surgery. Known as NEUSLeeP, the device combines gentle ultrasound stimulation with electrodes that track brain activity as it happens. This allows the patch to influence deep areas of the brain involved in sleep while also monitoring the brain’s response.

“This is the first time we’ve been able to noninvasively target deep brain regions involved in REM sleep, while simultaneously monitoring brain activity,” said Kai Wing “Kevin” Tang, a recent UT biomedical engineering Ph.D. graduate who led the research effort. “Our skin-attached NEUSLeeP patch opens up new possibilities for understanding sleep and treating sleep disorders in home settings,” added Huiliang “Evan” Wang, assistant professor in the Cockrell School of Engineering’s Department of Biomedical Engineering, who supervised Tang’s work and served as the principal investigator (PI) directing the overall project.

Wearable Patch Helps People Reach REM Faster

The researchers tested the technology in a study involving 28 people, with the results published in Nature Communications. On average, participants entered REM sleep 43 minutes sooner and remained in that stage for about 16 minutes longer.

The benefits were observed in both healthy sleepers and participants experiencing some sleep difficulties. Users also described the patch as comfortable and safe, and the study reported minimal adverse effects.

Possible Benefits for Stress and Emotional Health

Among healthy participants, NEUSLeeP stimulation also increased heart rate variability, which is commonly used as an indicator of the body’s ability to respond to stress. Brain imaging revealed changes in circuits associated with emotion, raising the possibility that the technology could support mood regulation and psychological resilience.

“REM sleep is not just about dreaming — it’s about emotional reset and stress adaptation,” explained Gregory Fonzo, assistant professor in the Dell Medical School’s Department of Psychiatry and Behavioral Sciences and one of the project’s co-PIs. “By enhancing REM, we may help people better cope with stress and improve their overall well-being.”

REM sleep disruptions have been associated with depression, anxiety and post-traumatic stress disorder (PTSD). Current approaches to sleep problems, including medication and behavioral therapy, may cause side effects or may not directly address the underlying factors that interfere with REM sleep.

Future Trials for Insomnia, Depression and PTSD

The team plans to conduct larger studies to verify the initial results and evaluate whether NEUSLeeP could help people with PTSD, depression and chronic insomnia. The researchers also see potential uses in home sleep monitoring, neuroscience research and personalized sleep treatments.

“Our vision is a future where patients with mental health disorders can optimize their sleep with a noninvasive and safe treatment,” said Vincent Mysliwiec, M.D., a professor at UT Health San Antonio, a leading expert in sleep disorders, and another co-PI on the project. “This technology could help millions of people get the restorative sleep they need.”

Certain imagery-based psychotherapy techniques may help reduce fear of failure connected to painful childhood experiences, according to research from scientists at SWPS University and the Nencki Institute of Experimental Biology. The findings were published in the journal Frontiers in Psychology.

Difficult experiences early in life, including criticism, neglect, or severe reactions from caregivers, can influence emotional well-being and quality of life years later. How adults respond when a child makes a mistake may be especially important in shaping future patterns of thought and emotion. In some cases, those experiences can contribute to a fear of failure rooted in the belief that mistakes make a person less worthy in the eyes of others.

Researchers from the Poznań-based Laboratory of Affective Neuroscience at the Institute of Psychology, SWPS University, and the Laboratory of Brain Imaging at the Nencki Institute of Experimental Biology in Warsaw set out to determine whether imagery-based psychotherapy could reduce the ongoing effects of these painful memories on everyday life.

Testing Whether Memory Work Can Create Lasting Change

The randomized, controlled clinical trial included 180 young adults (between 18 and 35 years of age) who experienced fear of failure. During a two-week period, participants took part in four therapy sessions focused on difficult childhood memories involving criticism.

One group used the Imagery Exposure (IE) technique. Participants were asked to recall situations that had triggered fear or anxiety (the active control group).

A second group received Imagery Rescripting (ImRs), a technique designed to change the way a memory unfolds in the imagination. Participants brought a distressing experience to mind and then imagined a “defender” (e.g., a therapist) entering the scene, confronting the person delivering the criticism, and offering support to the child.

The third group used the same therapeutic approach, but with a 10-minute delay procedure (ImRs-DSR). Researchers designed this delay to interfere with the memory trace associated with the critical experience, potentially strengthening the intervention’s effects.

Participants completed questionnaires and interviews, while researchers also tracked physiological measures. Follow-up assessments took place three and six months later.

Fear, Guilt, and Stress Declined

All of the imagery-based approaches produced a significant and lasting reduction in fear of failure. Participants also reported lower levels of negative emotions, including sadness and guilt.

Their bodies appeared to respond differently as well. Physiological reactions to memories of criticism decreased, indicating that recalling distressing experiences no longer triggered the same level of intense stress. These improvements remained evident during follow-ups at three and six months, suggesting that the psychological effects were stable over time.

“The study shows that it is possible to reduce the intensity of negative emotions and arousal associated with memories of childhood criticism. Properly selected techniques can influence how these memories are experienced, making them less burdensome,” says study co-author Julia Bączek, a psychologist from the Laboratory of Affective Neuroscience at the Institute of Psychology, SWPS University.

Why Surprise May Matter

The researchers found that imagery rescripting worked especially well when it produced a moment of surprise. They linked this effect to prediction error, which occurs when there is a mismatch between what someone expects and what actually happens.

That unexpected difference may help loosen established emotional patterns and make it easier for the mind to replace old, painful responses with new ones.

“We have shown that a crucial part of imagery-based therapy is creating a discrepancy between what the patient expects and what actually happens in the new memory. It is this surprise that paves the way for a lasting therapeutic change,” says study co-author Stanisław Karkosz, a cognitive scientist from the Laboratory of Affective Neuroscience at the Institute of Psychology, SWPS University.