Researchers from the University of Sydney's Lambert Initiative have provided much-needed scientific evidence that backs anecdotal claims that an accumulation of cannabinol (CBN) in older plants has a sleep-inducing effect. It's a minor compound in the plant, and far less understood and studied than tetrahydrocannabinol (THC) and cannabidiol (CBD).

"For decades, cannabis folklore has suggested that aged cannabis makes consumers sleepy via the build-up of CBN, however there was no convincing evidence for this," said lead author Jonathon Arnold, professor and director of preclinical research at the Lambert Initiative. "Our study provides the first objective evidence that CBN increases sleep, at least in rats, by modifying the architecture of sleep in a beneficial way."

In this animal study, the team monitored sleeping rats' brain patterns to specifically assess non-rapid eye movement (NREM) and rapid eye movement (REM). NREM sleep is a key restorative stage, also important in sustaining memory functions. REM sleep, where dreams take place, is needed for emotional processing and brain health.

"CBN was found to increase both NREM and REM sleep, leading to increased total sleep time, with a comparable effect to the known sleep drug zolpidem," Arnold said.

Zolpidem, known best by brand name Ambien, is a heavy sedative that has been known to cause nocturnal behaviors such as sleepwalking and 'sleep eating.' It can also cause next-day 'brain fog' and drowsiness.

While CBN's 'parent' molecule is the hallucinogenic THC, the researchers found that this cannabinoid only weakly activated the CB1 cannabinoid receptors in the brain and did not result in intoxication. However it did impact the areas of the brain involved in sleep, boosting REM and non-REM sleep.

"This provides the first evidence that CBN indeed increases sleep using objective sleep measures," said Arnold. "It was a surprise that CBN metabolism in the body can yield a much greater effect on cannabinoid CB1 receptors than the parent molecule CBN, which has much more limited activity."

As the researchers noted in the study: "CBN increased sleep stability as evidenced by longer duration NREM sleep bouts; this is significant as increased sleep stability has been associated with improved subjective sleep quality."