Since the 2018 Agricultural Improvement Act made it legal to grow and sell hemp-derived cannabidiol (CBD) products in the United States, CBD has seen a boom in popularity for a variety of use cases.
One of the most common reasons people turn to CBD is for help falling and staying asleep. But does the current scientific research support the idea that CBD makes you sleepy?
As is often the case with cannabis research, the answer depends on a range of factors. In this post, we’ll examine drowsiness as a side effect of CBD and explore whether CBD can help with certain sleep-related conditions.
If you’re interested in taking CBD during the day, you may be concerned about drowsiness as a side effect.
Those concerns have a backing in the current scientific understanding of CBD; a 2022 literature review found that drowsiness, lethargy, sedation, and fatigue were some of the most commonly reported side effects in a huge number of CBD studies going back to the 1980s.
A recent study published in March 2023 using a sample of 1,061 individuals, however, suggests that CBD may not cause daytime drowsiness — in fact, in some individuals, it may actually cause the opposite effect.
“CBD use was associated with a significant decrease in DD [daytime drowsiness]... in males >40 years of age,” based on measurements using the Stanford Sleepiness Scale (SSS), the study’s authors report.
“Only 4 of 851 individuals (0.5%) progressed from not having DD (SSS <5) to experiencing DD (SSS ≥5), while 43 of 49 (87.8) who initially had DD progressed to not having DD,” they add.
It’s worth noting that the participants in the 2023 study were all self-administering CBD and self-reporting their results, so the study’s results may contain some inaccuracies and instances of bias.
According to a 2023 literature review published in the journal Cannabis and Cannabinoid Research, there have been very few studies specifically examining CBD in relation to insomnia. Instead, many of the available studies examined blends of both CBD and THC.
Still, based on the available results, CBD may prove a viable alternative to other medications used for treating insomnia, especially for individuals who have experienced negative side effects as a consequence of taking those medications.
“All the 34 studies reported some level of improvement in the insomnia symptoms of at least a portion of their participants following the administration of CBD-containing products,” the review’s authors write.
Their findings indicate that CBD may work best for patients who experience insomnia as part of another wellness-related issue, however.
“The results of this systematic review suggest that CBD, either alone or in combination with equal amounts of THC, may be beneficial in the management of comorbid insomnia in patients with cancer, multiple sclerosis, psychiatric disorders, chronic pain, and PTSD,” the authors conclude.
“However, because only two included studies focused on patients with insomnia (including one case report), these results cannot be generalized to patients with primary insomnia.”
The authors go on to call for additional focused, high-quality research specifically studying CBD in relation to insomnia.
There is some evidence supporting the use of CBD to treat sleep problems caused by anxiety, and academic writing examining CBD in this context tends to note more pronounced improvements in relation to anxiety symptoms in general as opposed to anxiety-based sleep issues. Overall, however, the evidence comes mostly from case reports rather than proper clinical trials.
One series of case reports published in 2019, for example, found that anxiety symptoms and sleep improved thanks to CBD treatment lasting at least one month.
“Two months after the start of CBD treatment, 78.1% (32/41) and 56.1% (23/41) of patients reported improvement in anxiety and sleep, respectively, compared with the prior monthly visit,” the reports’ authors write.
It’s important to note, however, that another around a quarter of the patients found that their symptoms worsened again after 2 months of treatment, suggesting that there issues related to CBD tolerance may be at play.
A 2016 case study examining the treatment of a young girl suffering from sleep issues and anxiety symptoms in connection with posttraumatic stress disorder (PTSD) provides an optimistic outlook on how the initial symptom relief resulting from CBD can be a part of a longer treatment plan.
According to the study’s authors, the patient’s scores for anxiety and sleep issues decreased steadily over the course of five months, and the patient “was ultimately able to sleep through the night most nights in her own room, was less anxious at school and home, and displayed appropriate behaviors.”
“The ultimate goal is to gradually taper her off the use of CBD oil and transition our patient into lifelong coping strategies such as yoga, meditation, and various other therapeutic activities,” the authors add.
CBD has also garnered some attention in relation to rapid eye movement sleep behavior disorder (RBD), a common condition associated with Parkinson’s disease that can cause self-injuries and interrupt sleep.
Currently, different studies have reached opposing conclusions when examining CBD in this context.
One of the most recent studies, published in 2021, administered 300 mg of CBD to patients before bedtime for 12 consecutive weeks but found no improvement in RBD symptoms in comparison to a control group.
Interestingly, the researchers “observe significant improvement in sleep satisfaction” between the 4th and 8th weeks of the study among the participants who took CBD. The study’s authors call for more research with larger sample sizes, as well as different treatment periods with individuals in different stages of Parkinson’s disease to further clarify the efficacy of CBD in this context.
The authors of a slightly older series of four case reports, published in 2014, reached the opposite conclusion, writing that “the four patients treated with CBD had prompt, substantial and persistent reduction in the frequency of RBD-related events.”
The authors suggest that this outcome could shine further light on one hypothesis for how RBD manifests in patients based on CBD’s interaction with the endocannabinoid system. More specifically, the speculate that CBD’s action on CB1 receptors in the endocannabinoid system may cause the release of the neurotransmitter acetylcholine, which “plays a role in memory, learning, attention, arousal and involuntary muscle movement,” according to the Cleveland Clinic.
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