New research published in Journal of Psychopharmacology Studies suggest that psilocybin may improve subjective sleep quality in people suffering from chronic cluster headaches. This study provides evidence that this sleep improvement is proportional to a reduction in headache attacks and tends to be related to subtle differences in the physical structure of the brain. These findings provide a new perspective on how psychedelic compounds interact with sleep and brain health in patients with severe pain.
Sleep serves many important biological functions, including regulating fluid movement in the brain and removing waste products. During a healthy sleep cycle, the brain undergoes microscopic physical changes, such as changes 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 information processing, while white matter is made up of nerve fibers that connect different brain regions. Scientists believe that sleep is necessary to shrink neural connections made during the day and flush out cellular waste.
Sleep deprivation disrupts these maintenance processes and tends to lead to an unhealthy buildup of waste products in the brain. Chronic cluster headache is a severe neurological disorder characterized by frequent, severe pain on one side of the head, often accompanied by symptoms such as a runny nose and watery eyes. People with this condition often experience attacks at night, which severely disrupts their natural rest. Because of this persistent pain, patients often suffer from chronic sleep deprivation, which can lead to changes in the microstructure of the brain over time.
“Cluster headache attacks often occur at night, so cluster headache patients often have poor sleep quality,” says Christopher Brendstrup-Brix, MD and PhD student at the Neurobiology Research Unit at Copenhagen University Hospital in Rigshospitalet.
“Having previously found that psilocybin can reduce the number of headache attacks in cluster headache patients, we wanted to investigate whether sleep quality also improves after psilocybin.”
Blendstrup-Brix added that the research team is interested in the physical effects of these breaks in rest. “We and other researchers have shown that sleep may be involved in regulating brain structures such as the connections between neurons and the movement of water in the brain,” he said. “In this patient group, we can further investigate these relationships.”
Psilocybin is an active hallucinogenic compound found in certain types of mushrooms. Recent scientific interest has focused on its potential to treat a variety of psychiatric and neurological conditions, including cluster headache. Early observational reports indicate that psilocybin can reduce headache frequency over the long term. Some animal studies also suggest that psilocybin increases neuroplasticity, the brain’s ability to reorganize and form new neural connections.
Because sleep is essential for brain maintenance and psilocybin can promote structural changes in the brain, the researchers designed a study to examine changes in sleep quality and brain fluid dynamics after psilocybin administration. Researchers recruited 11 patients diagnosed with chronic cluster headaches from a Danish headache center. The group included five women, with an average age of about 49 years, who were experiencing at least four cluster headache attacks per week. As a point of comparison, the authors also included data from 24 healthy adults with an average age of about 33 years.
Healthy participants were sampled from separate imaging studies using exactly the same scanner settings to ensure consistency. The study included multiple brain scans and sleep assessments. Patients with cluster headaches underwent a special type of magnetic resonance imaging commonly known as an MRI. Specifically, the researchers used diffusion-weighted MRI, which tracks the movement of water molecules within the brain, to estimate the microstructure of brain tissue.
These scans were performed the day before the first psilocybin dose and 1 week after the last dose. By tracking the movement of water, scientists were able to calculate certain indicators about the brain’s internal environment. They measured the volume fraction within the neurite, which estimates the amount of water trapped within the neuron. They also looked at the average diffusivity outside neurites, which measures how freely water moves in the space outside brain cells.
Together, these metrics help us understand structural density and fluid stagnation within brain tissue. To measure sleep quality, participants completed the Pittsburgh Sleep Quality Index. This is a standardized questionnaire that asks individuals to rate their sleep habits and overall rest on a numerical scale.
In this study, the questionnaire was adjusted to reflect sleep quality over a one-week period. During the intervention phase, patients received three doses of a synthetic psilocybin formulation containing 0.14 milligrams of psilocybin per kilogram of body weight at one-week intervals.
Before psilocybin treatment, chronic cluster headache patients reported significantly worse sleep than the healthy group. Specifically, 10 out of 11 patients had significantly reduced sleep quality, compared to only 1 out of 24 healthy adults. 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 changes in gray matter.
After psilocybin intervention, patients experienced a significant reduction in headache symptoms. On average, the frequency of cluster headache attacks decreased by 50%, which equates to approximately 6 fewer attacks per week. Patients also saw an average decrease of 2.5 points on their sleep questionnaires and a 24% improvement in overall rest. This improvement in sleep scores directly reflected a reduction in weekly headache attacks, suggesting a strong relationship between symptom reduction and better rest.
Brendstrup-Brix said these improvements were the central findings of the study. “Our study confirms that cluster headaches are associated with sleep deprivation, and we found that after psilocybin administration, sleep improved in tandem with improvements in the number of headache attacks,” he told PsyPost. “We also found indications that both sleep and psilocybin may influence brain structure. However, these findings are not significant and need to be investigated further in larger studies.”
When the researchers examined brain scans after treatment, they found no statistically significant structural changes across the group. However, the data showed interesting trends in the individual results. Seven of the eight patients who completed the final scan showed numerical reductions in white matter intraneurite volume fraction and extraneurite mean diffusivity. This suggests that there were subtle changes in how water moves through white matter pathways after psychedelic therapy, perhaps suggesting slight changes in myelin content.
The authors also investigated the association between subjective sleep quality and brain microstructure. They found a borderline significant correlation between moderate muscle strength across both patients and healthy adults. This provides evidence that how well a person feels asleep is partially related to the physical movement of fluid within brain tissue. This data suggests that chronic sleep disturbances may lead to interstitial fluid stagnation, although the exact mechanism is not fully understood.
Although these findings are encouraging, there are also some limitations that require careful consideration. The most notable limitation is the small sample size. Only eight patients completed both baseline and follow-up brain scans. This small number makes it difficult to draw broad statistical conclusions and this result should be viewed as exploratory. The study also did not include a placebo control group, meaning some of the reported improvements may have been influenced by patients’ expectations rather than the drug itself.
Another limitation has to do with how sleep is measured. The researchers relied on self-report questionnaires, which capture an individual’s subjective perception of rest but may not reflect objective sleep structure. Future studies may benefit from recording brain waves and body movements during the night using objective monitoring tools such as polysomnography or wearable tracking devices. Tracking the exact timing of headache attacks could also help scientists determine whether psilocybin directly improves sleep or simply reduces the pain that causes night waking.
The techniques used to measure brain structure also rely on complex mathematical models that interpret the movement of water. These models make certain assumptions about brain organization that may not fully capture biological reality.
Additionally, improved sleep was closely linked to reduced headaches, making it difficult to distinguish between psilocybin’s direct effects on the brain and its indirect effects of reducing pain. Future studies with larger numbers of participants are needed to confirm these preliminary observations and further investigate how psilocybin affects brain health.
The study, “The 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, and Drummond E-Wen. McCulloch, Maja Lou Marstrand-Jorgensen, Sarah M. Ulb Larsen, Annette Johansen, Rigmor H. Jensen, Gitte M. Knudsen, and Martin K. Madsen.
