An Update on the Benefits of Cannabis for Sleep

Sleep disorders are widespread, and they impair our quality of life during the day. That underlies a growing interest in finding a safe and effective pharmacological intervention for poor sleep quality. (To learn more about the nature of sleep, go here.) Cannabis is being explored for several sleep disorders, including insomnia, obstructive sleep apnea, and restless legs syndrome.

Cannabis contains many active molecules, including Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD). In the old days, the original plant had about two molecules of THC for every single molecule of CBD. Today, that ratio is vastly different; thus, interpreting older studies that relied upon self-reports of cannabis use can be unreliable. What is currently well known is that THC is intoxicating but also shows proven anti-spasticity, mildly analgesic, anti-emetic, and appetite-simulant effects. CBD is not intoxicating and has mildly anxiolytic properties. Recent studies find that highly purified CBD is not consistently effective for seizure disorders. Previous positive reports on CBD were likely to be due to the presence of THC. (To learn more about how THC affects the brain, go here.) Recently, cannabinol, a degradative byproduct of THC with far milder intoxicating effects, as well as cannabigerol and cannabichromene, have been promoted as sleep aids despite no reliable supporting evidence.

The following paragraphs summarize the current state of our knowledge on the effectiveness of THC and CBD for three common sleep disorders.

Insomnia

Some research suggests short-term subjective sleep quality improvement with the psychoactive cannabinoids. However, short-term objective sleep benefits were associated with changes to important sleep stages. A mixture of THC and CBD reduced total sleep time and REM sleep duration and delayed REM sleep onset without changing subjective sleep quality. Essentially, people think that they sleep better with cannabinoids despite having highly distorted and unhealthy sleep patterns. These somnolent effects show tolerance over time that requires significant dose increases. Withdrawal from THC use typically produces significant nights of insomnia. Low doses of CBD provided no subjective benefits to patients with insomnia.

Obstructive Sleep Apnea

Mechanical devices, while effective, have poor long-term adherence. If you have ever tried to use one or slept alongside someone using one, you understand why. Preclinical studies suggest that cannabinoids might be effective. Cannabinoids, via their receptors, may modulate vagal feedback to the breathing centers in the brainstem medulla, leading to activation of upper airway dilatory muscles and easier breathing. In contrast, clinical trials on humans using the synthetic cannabinoid dronabinol have reported limited success. The American Academy of Sleep Medicine currently recommends that medicinal cannabis should not be routinely used due to insufficient evidence of effectiveness, tolerability, and safety.

Restless Legs Syndrome

One study evaluated the role of CBD in 18 patients with Parkinson’s disease and reported no improvement in subjective symptoms or objective sleep quality in these patients. In contrast, two case reports reported significant subjective improvements in 18 patients with restless leg syndrome and self-initiated cannabis use. Obviously, there’s a problem with potential subject bias in these two case reports. The National Restless Legs Syndrome Opioid Registry published a four-year update in December 2023. About half of the 423 registry participants reported benefits from opioid therapy. About one-quarter of the participants also used cannabinoids; most of these patients reported additional benefits by adding on THC.

The American Academy of Sleep Medicine released a position statement in 2018 on the use of medicinal cannabis in the treatment of these three sleep disorders. They recommended that medicinal cannabis should not be used in routine care due to insufficient evidence of effectiveness, tolerability, and safety. The evidence collected since then is insufficient to counter this recommendation.