Objective:

Background:

Insomnia is the most common sleep disorder. Traditional treatments can cause dependence and cognitive issues, prompting interest in medical cannabis (MC).

Design/Methods:

We conducted a Cochrane review (protocol https://doi.org/10.1002/14651858.CD016216), searching until April 2025. Included RCTs involving adults with insomnia comparing MC with placebo or other drugs. Outcomes included sleep quality, total sleep time (TST), adverse events, sleep onset latency (SOL), wake after sleep onset (WASO), daytime functioning, withdrawal symptoms and quality of life (QoL). We assessed the risk of bias using the Cochrane RoB2 tool. When feasible, we performed a meta-analysis, using RR for dichotomous outcomes and MD or SMD for continuous outcomes. The certainty of the evidence was appraised with GRADE.

Results:

We included nine studies (two parallel RCTs and seven crossover RCTs) with a total of 540 participants. Eight studies compared MC with placebo, and one compared it with amitriptyline. Most had an overall high risk of bias. MC may have little to no effect on sleep quality (SMD -0.58, IC95% -1.23 to 0.08), QoL (SMD 0.84, IC95% -0.61 to 2.29), and daytime functioning (SMD -0.34, IC95% -0.83 to 0.16) with a very low certainty. MC may have little to no effect on TST (MD 7.86, CI95% -23.04 to 38.39), WASO (MD -2.79, CI95% -34.40 to 28.82), and SOL (MD -4.30, CI95% -26.82 to 18.22). We could not meta-analyze adverse events due to insufficient information. One study reported withdrawal symptoms, but had no cases in either group.

Conclusions:

The studies analyzed to date suggest that MC has little or no effect on adult insomnia outcomes, with very low certainty of evidence. It´s recommended that, based on these preliminary analyses, further RCTs are required to address methodological limitations.