New research published in the Journal of Psychopharmacology suggests that psilocybin may improve subjective sleep quality in people suffering from chronic cluster headaches. The study provides evidence that this improvement in sleep is proportional to a reduction in headache attacks and tends to be associated with slight differences in the physical structure of the brain. These findings offer a new perspective on how psychedelic compounds might interact with sleep and brain health in patients with severe pain conditions.
Sleep serves many essential biological functions, including the regulation of fluid movement and waste removal in the brain. During healthy sleep cycles, the brain undergoes physical changes at a microscopic level, such as alterations in the density of nerve cell branches in the gray matter and changes in the fatty insulation called myelin in the white matter.
Gray matter is the tissue in the brain responsible for processing information, while white matter consists of the nerve fibers that connect different brain regions. Scientists believe that sleep is necessary to scale down neural connections made during the day and to allow for the washing away of cellular waste.
Poor sleep can disrupt these maintenance processes, which tends to lead to an unhealthy accumulation of waste products in the brain. Chronic cluster headache is a severe neurological disorder characterized by frequent, intensely painful headaches on one side of the head, often accompanied by symptoms like a runny nose or watery eyes. People with this condition often experience attacks during the night, which severely disrupts their natural rest. Because of this persistent pain, patients often suffer from chronic sleep deprivation, which might alter their brain’s microscopic structure over time.
“Cluster headache attacks most often occur at night, and patients with cluster headache therefore often have poor sleep quality,” said Kristoffer Brendstrup-Brix, an MD and doctoral student at the Neurobiology Research Unit at Copenhagen University Hospital, Rigshospitalet.
“Since we have previously found that psilocybin can reduce the number of headache attacks in patients with cluster headache, we wanted to investigate whether sleep quality also improved after psilocybin.”
Brendstrup-Brix added that the research team was curious about the physical effects of these rest disruptions. “We and others have shown that sleep may be involved in regulating the structure of the brain, such as the connections between neurons and the movement of water in the brain,” he said. “In this group of patients, we could explore these relations further.”
Psilocybin is the active hallucinogenic compound found in certain types of mushrooms. Recent scientific interest has focused on its potential to treat various psychiatric and neurological conditions, including cluster headaches. Early observational reports indicate that psilocybin can produce long-lasting reductions in headache frequency. Some animal studies also suggest that psilocybin increases neuroplasticity, which is the brain’s ability to reorganize and form new neural connections.
Because sleep is critical for brain maintenance and psilocybin may promote structural brain changes, researchers designed a study to examine changes in sleep quality and brain fluid dynamics after psilocybin administration. The researchers recruited eleven patients diagnosed with chronic cluster headache from a headache center in Denmark. This group included five females, with an average age of about forty-nine years, who were experiencing at least four cluster headache attacks per week. As a point of comparison, the authors also included data from twenty-four healthy adults with an average age of roughly thirty-three years.
The healthy participants were drawn from a separate imaging study that used the exact same scanner settings to ensure consistency. The study involved multiple brain scans and sleep assessments. The patients with cluster headaches underwent a specialized type of magnetic resonance imaging, commonly known as an MRI. Specifically, the researchers used diffusion-weighted MRI, which tracks the movement of water molecules in the brain to estimate the microscopic structure of brain tissue.
These scans were conducted the day before the first psilocybin dose and one week after the final dose. By tracking water movement, the scientists were able to calculate specific metrics about the brain’s internal environment. They measured the intra-neurite volume fraction, which estimates the amount of water trapped inside nerve cells. They also looked at extra-neurite mean diffusivity, which measures how freely water moves in the spaces outside of the brain cells.
Together, these metrics help paint a picture of structural density and fluid stagnation within the brain tissue. To measure sleep quality, the participants completed the Pittsburgh Sleep Quality Index, which is a standardized questionnaire that asks individuals to rate their sleep habits and overall restfulness on a numerical scale.
For this study, the questionnaire was adapted to reflect sleep quality over a one-week period. During the intervention phase, the patients received three doses of a synthetic psilocybin formulation, spaced one week apart, with each dose containing 0.14 milligrams of psilocybin per kilogram of body weight.
Before the psilocybin treatment, the patients with chronic cluster headaches reported significantly worse sleep than the healthy group. Specifically, ten out of the eleven patients had substantially impaired sleep quality, compared to only one out of the twenty-four healthy adults. The brain scans at the beginning of the study also revealed structural differences between the two groups. When the researchers analyzed the data together, they found that these baseline differences were primarily driven by variations in the gray matter.
Following the psilocybin intervention, the patients experienced a noticeable reduction in their headache symptoms. On average, the frequency of their cluster headache attacks dropped by fifty percent, equating to about six fewer attacks per week. The patients also saw an average drop of 2.5 points on their sleep questionnaire, representing a twenty-four percent improvement in overall restfulness. This improvement in sleep scores directly mirrored the reduction in weekly headache attacks, suggesting a strong relationship between symptom relief and better rest.
Brendstrup-Brix noted that these improvements were a central outcome of their research. “In our study, we confirm that cluster headache is accompanied by poor sleep, and we find sleep to improve after psilocybin in parallel with an improvement in the number of headache attacks,” he told PsyPost. “We also find indications that both sleep and psilocybin may have effects on the structure of the brain, although these findings were not significant and should be investigated further in larger studies.”
When the researchers looked at the brain scans after the treatment, they did not find statistically significant structural changes across the group as a whole. However, the data revealed an interesting trend in the individual results. Seven out of the eight patients who completed the final scan showed numerical decreases in their white matter intra-neurite volume fraction and extra-neurite mean diffusivity. This suggests a subtle shift in how water moved through the white matter pathways after the psychedelic therapy, possibly hinting at slight changes in myelin content.
The authors also looked for connections between subjective sleep quality and the microscopic structure of the brain. They found borderline significant correlations of moderate strength across both the patients and the healthy adults. This provides evidence that how well a person feels they sleep is partially linked to the physical movement of fluids within their brain tissue. The data suggests that chronic sleep disturbances might lead to a stagnation of interstitial fluid, though the exact mechanisms are not fully understood.
While these findings are encouraging, they come with several limitations that require cautious review. The most prominent limitation is the small sample size, as only eight patients completed both the baseline and follow-up brain scans. This small number makes it difficult to draw broad statistical conclusions, and the findings should be viewed as exploratory. The study also lacked a placebo control group, meaning some of the reported improvements could be influenced by the patients’ expectations rather than the drug itself.
Another limitation relates to how sleep was measured. The researchers relied on self-reported questionnaires, which capture a person’s subjective perception of their rest but may not reflect objective sleep architecture. Future research could benefit from using objective monitoring tools, such as polysomnography or wearable tracking devices, to record brain waves and physical movements during the night. Tracking the exact timing of headache attacks could also help scientists determine if psilocybin improves sleep directly or simply reduces the pain that causes nighttime awakenings.
The techniques used to measure brain structure also rely on complex mathematical models to interpret water movement. These models make certain assumptions about brain tissue that may not perfectly capture the biological reality.
Additionally, because sleep improvements were so closely tied to a reduction in headaches, it is difficult to separate the direct effects of psilocybin on the brain from the indirect benefits of experiencing less pain. Future studies with larger numbers of participants are needed to confirm these preliminary observations and further explore how psilocybin influences brain health.
The study, “Effects of psilocybin on sleep quality and brain microstructure in chronic cluster headache,” was authored by Kristoffer Brendstrup-Brix, Brice Ozenne, Patrick M. Fisher, Dea S. Stenbæk, Anja S. Petersen, Sophia Armand, Drummond E-Wen. McCulloch, Maja Rou Marstrand-Joergensen, Sara M. Ulv Larsen, Annette Johansen, Rigmor H. Jensen, Gitte M. Knudsen, and Martin K. Madsen.