Cannabinol: What is CBN?
Cannabinol or CBN (figure 1) is one of the hundreds of cannabinoids found naturally in cannabis and hemp and is what some refer to as the “sleeper cannabinoid” due to how it makes some users drowsy. But while research is still in its infancy, there are more factors that contribute to what users describe as that sleepy feeling. This article aims to clarify what exactly CBN is and its effects on the body with what more modern research points to in terms of the possible benefits of this cannabinoid.
Figure 1. The chemical structure of cannabinol (CBN)
What is CBN?
CBN was one of the first cannabinoids to be identified and studied as early as 1899 by Thomas Barlow Wood, W.T. Newton Spivey, and Thomas Hill Easterfield  and purified and isolated in 1940 by Roger Adams, Madison Hunt, and J.H. Clark . CBN has a chemical structure very similar to tetrahydrocannabinol (THC) with one of the major differences being the cyclohexene ring  being turned into a benzene ring . This change occurs naturally through a process called oxidative degradation  (figure 2) where a combination of UV light, heat, and the presence of oxygen takes those extra hydrogen atoms in the ring and converts them into a benzene ring effectively changing the structure and properties  of the molecule to CBN.
Figure 2. The oxidative degradation of THC to CBN with the changes circled in red
Effects of CBN
While CBN is very closely related to THC and has similar effects on users, CBN does not have the same psychoactive effects associated with THC, instead, some sensitive users report a much more mild psychoactive effect. Initially, CBN was thought to make its users drowsy but it's actually when combined with THC that users feel the effects of drowsiness from THC are amplified .
CBN interacts with the endocannabinoid system  just like all other cannabinoids. Research on how the mechanism  in which it interacts with the endocannabinoid system is slowly progressing. CBN has an affinity for both the CB1 and CB2 receptors, showing a higher affinity for CB2  but not as high of an affinity as its original predecessor THC. Some studies have shown that CBN can increase appetite as opposed to the effects of cannabidiol (CBD) and cannabigerol (CBG) . Other studies have shown that it has antibacterial effects on the body , reduces seizures , and even delays the onset of amyotrophic lateral sclerosis (ALS) .
IS CBN Legal?
As with most cannabinoids, their legality of them is always up for debate. In the United States, CBN derived from a marijuana extract is illegal and considered a Schedule I controlled substance, according to the Drug Enforcement Agency (DEA) . However, according to the Agriculture Improvement Act of 2018, if CBN is extracted from hemp it is perfectly legal, provided the THC content is below 0.3% on a dry weight basis .
While the United States has some limitations on the cannabinoid, the United Kingdom considers CBN and any of its derivatives a controlled substance  per the Misuse of Drugs Act 1971and is outright illegal to produce from hemp or marijuana, as well as illegal to consume . The United Kingdom’s reasoning for keeping CBN illegal, despite motions to downgrade its status , is from a literature review where they found that of all the forms of CBN, only one showed any sort of psychoactive effects in test subjects , but that one study was enough for the advisory council to keep CBN on the Class B Schedule 1 list in the Misuse of Drugs Act 1971 along with substances such as amphetamines and barbiturates.
 Benzene | C6H6