CBN is a commonly discussed cannabinoid that stands for Cannabinol.
Many people associate CBN with drowsiness, and therefore a good choice for insomnia. Studies have shown that CBN on its own does not necessarily promote drowsiness, but it does amplify sleepy effects when combined with THC.
CBN is a cannabinoid that is found in higher concentrations in older flower samples. The terpene mixture found in cannabis flower also tends to change over time. Monoterpenes are very reactive to their environment and will disappear over time, leaving the larger, more stable sesquiterpenes behind. These sesquiterpenes often account for drowsiness, and could be another explanation to why older cannabis flower has a sleepier effect.
As usual, much research is to be done in the area of cannabis, and we are looking forward to keeping up to date with new information!