Is cannabidiol an effective treatment of insomnia in adults?
A recent systematic review from 2020 investigated cannabinoid therapies for various sleep disorders. The review included 14 preclinical studies and 12 clinical studies (N=250). We found no published randomized controlled trials of cannabinoids in clinician-diagnosed insomnia. Only two studies specifically addressed cannabidiol (CBD) for insomnia in adults. One retrospective study (n=72) looked at self-administered 25 to 75 mg oral capsules CBD for psychiatric patients diagnosed with a sleep or anxiety disorder, with exclusion of patients with primary diagnosis of schizophrenia, post-traumatic stress disorder, or agitated depression. Sleep improvement was evaluated by Pittsburgh Sleep Quality Index (PSQI), which is a self-reported measure that assesses sleep quality based on a 19-item questionnaire. PSQI has a maximum score of 21 and higher scores equate to worse sleep. Mild improvement in sleep was seen in the sleep disorder group (n=25) evidenced by decreased PSQI (baseline 13.08-9.33 after 3 months). Another small study looked at oral capsule CBD (40, 80, and 160 mg) versus placebo and a control (nitrazepam 5 mg) in healthy adult volunteers complaining of sleep difficulties. CBD was taken 30 minutes before bed, and self-reported increase was noted in sleep duration (two-thirds of patients reported sleeping >7 hours, P ≤ .05 over baseline) in the group receiving 160 mg CBD. However, the study was a small sample (n=15) of researcher family members with subjective complaints of poor sleep and was measured with a nonvalidated 10-question sleep questionnaire. Limitations of this systematic review included English-only articles, small sample sizes, poor methodological quality, and high risk of bias.
One longitudinal cross-sectional study investigated cannabis use for anxiety and insomnia. One hundred fifty-two regular users, 21 to 70 years old, with mild anxiety disorders (Generalized Anxiety Disorder-7 score 5 or more) were surveyed using the PSQI. Regular use was defined as use of smoking, vaporization, or edible consumption at least once per week. Regression analysis was used to determine association between sleep and cannabis use, and P-values were adjusted for multiple variables, including age and amount of cannabis use. β co-efficient reflects the strength of the effect of cannabis use on different variables, with higher values indicating a stronger effect. Self-reported current use and more days of cannabis use were associated with increased expectation of improved sleep (β=0.03, P=.04). However, this was associated with worse subjective sleep quality (β=1.34, P=.02). This study was limited because of the sample being primarily white women with comorbid anxiety disorders. Tetrahydrocannabinol (THC)/CBD concentrations were self-reported increasing risk for recall bias, and THC's psychoactive properties may have had an impact. In addition, cross-sectional design limits the strength of evidence.
O'Neill S, Patalinghug E. Is cannabidiol an effective treatment of insomnia in adults? Evidence-based practice : patient-oriented evidence that matters 2022;25(6):11.doi: 10.1097/EBP.0000000000001499.