In recent years, marketers of cannabis (i.e., marijuana) products have claimed that cannabinol (CBN) has unique sleep-promoting effects. Despite a plausible mechanism, it is possible that such claims are merely rooted in cannabis lore. The aim of this narrative review was to answer the question: "Is there sufficient clinical evidence to support claims that CBN has sleep-promoting effects?" A systematic search of PubMed/MEDLINE was performed to evaluate the published evidence. The abstracts of 99 human studies were screened for relevance by the author and reviewed for compliance with the inclusion criteria. The characteristics and principal findings were extracted from eight full-text articles that met inclusion criteria for detailed review. Pre-clinical and clinical research investigating the effects of CBN is dated and limited, with the preponderance of human studies occurring in the 1970-1980s with small sample sizes lacking diversity in sociodemographic characteristics. Studies specifically assessing subjective effects associated with sleep, such as sedation or fatigue, are rare. Most importantly, published clinical trials investigating associations between CBN and validated sleep questionnaires and/or formal polysomnography were not identified in this review. In addition, evidence demonstrating that CBN itself elicits cannabis-like effects in humans is mixed, with the majority of available evidence demonstrating a lack of such an effect. Consequently, there is insufficient published evidence to support sleep-related claims. Randomized controlled trials are needed to substantiate claims made by manufacturers of cannabis products containing CBN. These studies should specifically evaluate its effects on sleep through polysomnography, or at minimum, through validated sleep questionnaires, and use dosages significantly higher than those found in currently available cannabis products marketed for sleep (typically ≤5 mg). Individuals seeking cannabis-derived sleep aids should be skeptical of manufacturers' claims of sleep-promoting effects.
Keywords: CBN; THC; cannabinoids; cannabis; marijuana; sleep.