Taking a pill containing cannabis compounds might alter sleep patterns for individuals with mild to moderate insomnia, mostly by reducing the amount of time spent in the specific sleep phase associated with dreaming. A single dose of a medication combining tetrahydrocannabinol and cannabidiol shortened total sleep duration in a small group of adults but left their next-day alertness largely intact. These findings were published in the Journal of Sleep Research.
Insomnia disorder is a widespread condition affecting a vast portion of the adult population. It involves persistent difficulty initiating or maintaining sleep over several months, resulting in daytime sleepiness or fatigue. Standard treatments like cognitive behavioral therapy can take weeks to yield benefits and demand time and effort from the patient. Seeking faster relief, many people turn to pharmaceutical sleep aids or prescription sedatives.
These conventional sleeping pills often bring unwanted side effects, ranging from dizziness to grogginess the following morning. Because of these drawbacks, a growing number of patients are turning to medicinal cannabis as a potential alternative. People frequently use cannabis products to self-medicate for sleep, hoping to substitute their prescription medications with a plant-based option. Despite this popularity, actual clinical trials testing cannabis compounds on objective sleep metrics remain scarce.
Anastasia Suraev, a researcher at the University of Sydney and the Woolcock Institute of Medical Research, led a team to investigate how cannabis constituents affect the sleeping brain. The researchers wanted to measure the precise impact of an oral dose of cannabis on the biological stages of sleep. They also aimed to see if the medication left users impaired the next day. To do this, the team focused on two primary compounds found in the cannabis plant: tetrahydrocannabinol and cannabidiol.
Tetrahydrocannabinol, or THC, is the main intoxicating compound responsible for the behavioral effects associated with marijuana. Cannabidiol, or CBD, does not produce this intoxicated state but is often marketed for relaxation or pain relief. The research team formulated an oil containing ten milligrams of THC and two hundred milligrams of CBD. They chose this specific formulation because early clinical data suggested a higher amount of CBD might help mitigate some of the less desirable effects of THC.
The trial included twenty adults diagnosed with clinical insomnia disorder. None of these individuals had used cannabis in the three months prior to the study. This allowed the research team to evaluate the biological effects on people who had not built up a tolerance to the drug. The study utilized a crossover design, meaning each participant received either the active cannabis oil or a visually identical placebo on two separate nights.
Such a design allows researchers to compare how the exact same person responds to both the cannabis formulation and the inactive placebo. The trial was mutually blinded, preventing both the patients and the researchers from knowing which treatment was administered on a given night. Giving each person both interventions separated by at least a week helps eliminate alternative explanations for the results. On the night of the experiment, participants took their assigned dose of oil one hour before getting into bed.
While the participants slept in a clinical laboratory, researchers recorded their brain activity using electroencephalography, or EEG. The team used a specialized sensor cap containing two hundred and fifty-six individual electrodes. These electrodes detect tiny electrical signals generated by groups of neurons communicating in the brain. By mapping these electrical waves across the scalp, sleep technicians can track when a person moves through different stages of sleep.
Sleep typically cycles through lighter stages, deeper restorative stages, and rapid eye movement sleep. The deep stages are often characterized by slow, rolling brain waves, and this time is thought to be essential for physical rest. Rapid eye movement sleep is the stage during which most vivid dreaming occurs. The brain becomes highly active during this paradoxical phase, resembling a state of waking consciousness despite the body remaining entirely still.
The electrical recordings revealed that the cannabis combination shortened total sleep time by an average of twenty-five minutes compared to the placebo night. It also decreased the total amount of time spent in the rapid eye movement stage by about thirty-four minutes. The drug pushed back the timing of this dreaming phase, adding over an hour to the onset of rapid eye movement sleep. The amount of time participants spent awake in the middle of the night did not experience any noticeable changes.
A closer look at the high-density brain mapping revealed additional changes in sleep quality. During the lighter stages of restful sleep, the cannabis oil reduced high-frequency brain waves, a modification that suggests a calming of cortical arousal. However, during the deepest sleep stages, the drug decreased the intensity of slow wave activity. This dampening of slow waves points to a reduction in sleep depth, which could limit the physically restorative quality of rest.
During the rapid eye movement stage, the cannabis treatment prompted an increase in fast-paced brain rhythms in the posterior regions of the brain. This electrical signature indicates a state of heightened arousal while the patient is still asleep. These findings align with prior research involving recreational marijuana users, showing that THC acts as a strong suppressor of dreaming phases. Hypnotic medications like benzodiazepines typically produce similar disruptions to the normal electrical structure of a night of sleep.
After investigating the overnight patterns, the researchers wanted to know how the patients functioned the next day. A common issue with traditional sleep aids is the persistence of drug effects after the patient wakes up, which can present a hazard for driving or working. Starting the morning after treatment, participants completed multiple rounds of cognitive and behavioral tasks. These tasks measured their ability to maintain attention and react quickly to visual cues on a computer screen.
The participants performed just as well on the attention tasks after taking the cannabis oil as they did after the placebo. The researchers also administered a recognized clinical assessment designed to test an individual’s ability to resist falling asleep in a dark, quiet room. During this trial, the time it took participants to drift off did not differ between the two conditions. The experimental team did not observe statistically significant differences in objective daytime cognitive performance.
The patients did fill out subjective surveys regarding their daytime mood and energy levels. People reported feeling a slight increase in general sleepiness the day after consuming the cannabis oil. This translated to a mild sense of drowsiness, yet it failed to interfere with their physical reaction times or ability to stay awake under observation. Minor side effects like a dry mouth were common, but no major adverse events occurred during the observation windows.
The researchers outline a few caveats to consider regarding the study design. The investigation involved a small group of volunteers, which means the results might not perfectly replicate across a massive population. The participants also slept on a fixed eight-hour schedule to accommodate the strict timing of the morning reaction tests. This structured timeline might have hidden some natural recovery sleep that a person would otherwise achieve at home without an alarm clock.
This particular trial only looked at the biological consequences of a single dose over the course of a solitary night. Individuals seeking relief from chronic insomnia usually take remedies on a nightly basis over long stretches of time. Without testing sequential nights, the research cannot predict whether patients might build a tolerance to the drug or experience withdrawal symptoms upon quitting. Rebound insomnia and intense dreams are known withdrawal symptoms for heavy cannabis users when they abruptly stop taking the substance.
The specific ratio of active ingredients introduces another variable for future exploration. The market features countless marijuana products containing unpredictable blends of active compounds. A product bearing a higher concentration of tetrahydrocannabinol and a lower dose of cannabidiol might trigger entirely different physiological reactions or unwanted side effects. Future clinical work will need to track people over weeks of continuous use to understand the long-range safety profile of medicinal cannabis.
The study, “Acute Effects of Oral Cannabinoids on Sleep and High-Density EEG in Insomnia: A Pilot Randomised Controlled Trial,” was authored by Anastasia Suraev, Iain S. McGregor, Danielle McCartney, Nathaniel S. Marshall, Chien-Hui Kao, Rick Wassing, Angela L. D’Rozario, Keith K. H. Wong, Brendon J. Yee, Sheila Sivam, Richard C. Kevin, Ryan Vandrey, Christopher Irwin, Christopher J. Gordon, Delwyn Bartlett, Jonathon C. Arnold, Ronald R. Grunstein, and Camilla M. Hoyos. The research work was primarily completed at the Woolcock Institute of Medical Research in Sydney, Australia.
