CBN is claimed to have sedative and sleep-promoting effects. The problem is that very little of the extensive research on CBN actually supports this.

Cannabinol (CBN) is not produced directly from the cannabis plant, but rather is a breakdown product of THC that is generated by prolonged storage or heat.

CBN is most famous for sedative effects and promoting sleep. At least that is what you read just about everywhere. Most websites describe this very generally, but Steep Hill Labs makes some very specific claims:

“Of all the cannabinoids, CBN appears to be the most sedative. Not only is it sedative, it takes very little to do the job. The consumption of 2.5mg to 5mg of CBN has the same level of sedation as a mild pharmaceutical sedative, with a relaxed body sensation similar to 5mg to 10mg of diazepam.”

I thought this article would be a straight-forward one. However, when I combed through the research (much of it dating back to the 70’s and 80’s), I actually found very little data to support this claim. There is one study that everyone cites to say that CBN is sedative, but an in-depth analysis will show that the findings weren’t very strong.

I am now questioning whether CBN as a sleep-promoting sedative has been wrong this whole time. You can read summaries of the scientific studies below and decide for yourself:

Clinical Studies of CBN (IV & Smoked)

Six healthy males were administered an IV infusion of CBN at a rate of approximately 1.2 mg/min. It took about 200 ug/kg (around 14 mg) for subjects to perceive any subjective effects and for heart rate to increase by 25% (an effect that is mediated by brain CB 1 receptor activation).

Subjects reported the experience to be “mild and enjoyable”, but said that it was not as intense as smoking cannabis.

Six healthy males were administered CBN (20 mg) over a 2 min IV infusion. On another occasion, they smoked a “placebo” joint (with virtually no THC) over 3 minutes that was spiked with 20 mg of CBN.

Although subjective effects were not formally assessed (since this was primarily a pharmacokinetic study), there were “no psychoactive effects noted“. The bioavailability of smoked CBN was 39%, in case you were curious.

Clinical Studies of CBN (Oral)

Six male subjects were administered oral doses of CBN that ranged from 20 mg up to 400 mg. The investigators reported that “at no oral dose level were any of the characteristic mental or physical effects of THC observed.”

Five male volunteers were given oral CBN (50 mg) or placebo on different occasions. No increase in heart rate was observed and subjects reported no subjective effects at any time point. “The present data show that the 50 mg dose of CBN was inactive.”

[Note: This study also assessed CBN in combination with THC, which I will report in the next section.]

In this double-blind, placebo-controlled study, subjects were administered oral CBN (320 ug/kg, or about 22.4 mg) and given a battery of perceptual, cognitive, and motor function tests. “CBN [was] without significant effect on any of the parameters studied.”

Clinical Studies of CBN Combined With THC

Fifteen healthy male subjects were administered oral THC (20 mg) combined with either placebo or with CBN (40 mg) on different occasions.

CBN did not affect heart rate or subjective drug effects when combined with THC. “No quantitative or temporal difference was observed between THC-placebo and THC-CBN in terms of clinical effects. Qualitatively each treatment produced identical effects.”

The second study had basically the same design, but it was a pharmacokinetic study to assess whether CBN could change the blood levels of THC. No significant effect of CBN on the pharmacokinetics of THC was observed, although there was a trend toward CBN increasing levels of THC.

Five male subjects were administered oral THC (25 mg) combined with the following oral doses of CBN on different occasions: 0 mg, 12.5 mg, 25 mg, and 50 mg.

This is the one study where CBN was reported to modify the effects of THC: “With combined drug treatment, volunteers reported feeling more drugged, drunk, dizzy, and drowsy than under the THC condition alone.” Here is the original figure (which I will analyze in-depth in the next section):

Critical Analysis of Clinical CBN Data

For CBN that was given IV and smoked, the two studies conflict with each other. The first noted a very mild THC-like effect, and the second observed no psychoactive effect, even though they tested both a slightly higher IV dose and smoked CBN that was the equivalent of a lower IV dose (due to lower bioavailability). The mild effect from the first study could be real or just placebo, but neither study noted any sedative effects

For CBN that was given orally, three independent studies all reported no detectable effects with doses ranging from 20 mg to 400 mg. Although they didn’t specifically assess sedation, surely this would have been an observation if the effect was significant. For comparison, if a 5 or 10 mg dose of diazepam was given in a blinded fashion, sedation would absolutely be a noted effect.

Finally, let’s get to the two studies that combined CBN with THC. The first study did not note any effects of CBN at all, and the second showed that CBN modified 4 different items in a 66-item scale of subjective effects: drugged, drowsy, drunk, and dizzy (the 4 D’s!).

This is the study that everyone cites to support sedative effects, but when we examine it closer, the findings are actually very weak.

Small sample size : This study included ONLY 5 SUBJECTS.

: This study included ONLY 5 SUBJECTS. Multiple comparisons : The subjective effects assessment they used had 66 items, and there were 3 different CBN dose groups that were compared to THC alone. With 198 comparisons, it is not surprising that a few of them would come out statistically significant by chance.

: The subjective effects assessment they used had 66 items, and there were 3 different CBN dose groups that were compared to THC alone. With 198 comparisons, it is not surprising that a few of them would come out statistically significant by chance. No consistent dose-response: Out of the 4 items, there was no consistent dose-response. Sometimes the higher CBN doses were different, sometimes only the lowest dose, sometimes only the highest and lowest, but not the middle. This looks more to me like random noise than an actual drug effect.

Let’s dive in even deeper on the “drowsy-alert” item as this is the one that should be modified most by a sedative effect. Note that this is basically a 9 point scale (4 in the direction of alert, one neutral, and 4 in the direction of drowsy). What they are plotting is a change from baseline before drug was given.

They don’t include any error bars or confidence intervals in the original plot, but they did give the standard error values. I have taken the liberty of replotting the data with the means and 95% confidence intervals:

Including the confidence intervals makes the differences look much less impressive. There is absolutely no change with 12.5 mg CBN and a 1 point increase (on a 9 point scale) with 50 mg CBN, even though this dose is way above what most people are claiming to be active. Although it was statistically significant, this does not make it a robust finding for all the reasons I have mentioned previously (extremely small sample size, no compensation for multiple comparisons, lack of confirmation in other studies, etc.).

Let’s assume for a moment that the effect is real. Remember the pharmacokinetic study described above, where there was a trend toward CBN boosting THC levels? That interaction alone could explain this finding. Adding 50 mg of CBN may just be the equivalent of boosting your THC dose by a little bit. If this is the case, CBN is not actually adding anything unique to the sedative effects of THC.

Animal Studies of CBN

I won’t review every study done in animals, but focus on examining whether there is any possible confirmation of CBN’s putative sedative or sleep-promoting effects. CBN at times has shown cannabimimetic properties in animals, but the results have been quite inconsistent.

The first study ever done that showed an effect of CBN in animals was performed in 1945! It showed that CBN produced ataxia (motor incoordination) in dogs at doses of 12 mg/kg and up. Although many sedatives can produce ataxia (e.g. alcohol, barbiturates, benzodiazepines), I have never heard of CBN doing this in humans.

CBN by itself had no activity when given IV to monkeys and did not change the effects of THC.

One study showed that CBN prolonged barbiturate sleeping time in mice (indicating sleep-promoting effects), but a different mouse study contradicted these results. Although THC has very strong sleep-promoting effects in this assay, CBN antagonized these effects of THC. This is completely the opposite of what you would expect for a synergistic interaction.

Overall, the animal studies do not support sedative effects of CBN.

Effects of CBN at CB 1 and CB 2 Receptors

Can we understand anything more by understanding the pharmacological mechanisms of CBN? Here is what we know:

CBN can bind both CB 1 and CB 2 receptors with reasonable affinity (although not quite as high as THC). It appears that CBN is a relatively weak partial agonist at both receptors. Since the CB 2 receptor is not involved in sedation or sleep, we can ignore this mechanism.

CB 1 receptor activation can certainly result in sedation and increased sleep (as evidenced by THC). But CBN activates the CB 1 receptor very weakly, so this does not really explain its effects. And it certainly would not suggest any synergy with THC. If anything, it would functionally act as an antagonist in the presence of THC and reduce its effects. This was, in fact, what was seen in one of the animal studies above.

CBN does have an active metabolite, called 11-OH-CBN, that is a more potent CB 1 partial agonist. But this alone doesn’t give us any additional insight or explain the (lack of) observed clinical sedative effects of CBN.

Conclusions on CBN Sedative Effects

Without any adequate study focused specifically on sedative or sleep effects of CBN, I cannot say for sure whether it has these effects or not. But I find it extremely surprising that these effects were barely noted in any of the clinical studies. More companies are developing CBN products and marketing them as sleep aids and I would like to see evidence to back it up.

Could it be possible that the hundreds of websites claiming sedative effects of CBN are wrong? This would not be the first time that some “common knowledge” about cannabis turned out to be incorrect. Remember that 99% of what you read on the internet is just people copying other stuff they read on the internet. So the mere fact that you read this everywhere does not make me believe it any more.

Where did the assertion that CBN is sedative come from originally? I have primarily heard that it comes from the observation that aged cannabis (which does have higher levels of CBN) is more sedative. This could very well be true, but the correlation does not mean that CBN is causing the sedative effect. There could be other breakdown products (oxidized terpenes for example) with pharmacologic activity that causes a sedative effect.

From a mechanistic perspective, a weak CB 1 agonist like CBN could potentially cause mild sedation. But it wouldn’t be doing anything different than a low dose of THC, so it is not really that exciting to me. And it wouldn’t have any particular synergism with THC like some people claim. So if this actually turns out to be true, then CBN would have to have some totally different mechanism of action that has not yet been discovered. However, no data that I am aware of yet supports this.

Based on US and EU databases, there are currently no plans for formal clinical testing of CBN. However, a relatively quick clinical trial could provide some clear answers one way or the other on whether CBN is useful for sleep.