Cannabis and sleep architecture: A systematic review and meta-analysis.

Cannabis use for sleep is increasingly prevalent, yet its effects on sleep architecture remain unclear. This systematic review and meta-analysis examined polysomnographic evidence on cannabis' impact on sleep parameters. Eighteen studies were identified, with nine suitable for meta-analysis. Findings indicate that cannabis administration does not consistently alter sleep duration, latency, wake time, efficiency, or sleep staging. While early studies suggested reductions in rapid eye movement sleep, these were primarily based on small-scale trials with high tetrahydrocannabinol doses and significant methodological limitations. More recent studies using larger samples and lower therapeutic doses of tetrahydrocannabinol have reported mixed (and often no) evidence of rapid eye movement (REM) suppression, and the evidence base remains very limited. However, withdrawal from active cannabis use was consistently associated with sleep disturbances, including reduced total sleeping times and prolonged sleep onset latency, as well as REM rebounds. Variability in study outcomes highlights the influence of factors such as dosage, cannabinoid composition, prior cannabis use, and health conditions. Further research using standardised protocols and larger samples is needed to clarify the relationship between cannabis and sleep architecture and to address the discrepancies between subjective sleep improvements and objective sleep metrics.