Effectiveness of cannabinoids on subjective sleep quality in people with and without insomnia or poor sleep: A systematic review and meta-analysis of randomised studies.

STUDY OBJECTIVES: This systematic review and meta-analysis assessed the efficacy of cannabinoids compared to placebo for improving sleep quality. METHODS: Searches were conducted in MEDLINE, Embase, and Cochrane databases for randomised controlled trials comparing cannabinoids vs. placebo for improving sleep quality in adults with or without insomnia or poor sleep. The primary outcome was self-reported sleep quality (PROMIS, PSQI, LSEQ, Sleep Diary). Secondary outcomes included actigraphy parameters, anxiety (GAD-7, STAI-T), well-being (WHO-5 index), and insomnia severity (ISI). Additional analyses focused on sleep quality in (1) participants with insomnia or poor sleep, and (2) cannabidiol (CBD) vs. non-CBD interventions. Statistical analysis was performed using RevMan 5.4.1, with p < 0.05 considered significant. RESULTS: Six trials (1077 patients) were included. Cannabinoids significantly improved sleep quality compared to placebo [SMD 0.53; 95 % CI 0.03-1.02; p = 0.04; I2 = 88 %], particularly in those with insomnia or poor sleep [SMD 0.60; 95 % CI 0.09-1.11; p = 0.02; I2 = 89 %]. Non-CBD cannabinoids demonstrated greater efficacy [SMD 0.82; 95 % CI 0.24-1.40; p = 0.005], whereas CBD-only therapies showed no significant effect [SMD 0.13; 95 % CI -0.38-0.65; p = 0.61]. CONCLUSION: Cannabinoids, particularly non-CBD formulations, improve sleep quality, justifying further investigation as therapeutic options for insomnia or poor sleep.