For many people, cannabis and sleep go hand-in-hand. Smoking a heavy-hitting indica strain before bed is a tried and tested sleep aid and a sure-fire way to catch maximum Z's once your head hits the pillow. What happens after you enter the Land of Nod, however, can sometimes be a little funky, as cannabis does have a tendency to alter people's dreams.
What Dreams Are Made Of
It's a common misconception that we only dream during the stage of sleep known as rapid eye movement (REM). While it's true that most dreams do occur at this point in the sleep cycle, they can also pop up during non-rapid eye movement (NREM) sleep.
The majority of our time spent snoozing is taken up by NREM, which is split into three separate stages labelled N1, N2 and N3. Not to be confused with London postcodes, these phases make up our beauty sleep and allow the body and mind to rest and recharge. N3, in particular, is synonymous with slow wave sleep, which is the deepest of deep sleep and largely to thank for our ability to feel rested when we wake up in the morning.
Dreams can occur during any of these sleep stages, and it's thought that about 20 per cent of all nocturnal fantasies arise in the NREM phase. Typically, these dreams are rather mundane and unspectacular, although luckily, they aren't the ones we remember as we rarely wake up at this point in our slumber.
It's during the REM stage that the party really gets started. As the brain becomes more active and the eyes start dancing around behind the eyelids, dreams become crazier and more abstract. Despite spending less than a quarter of the night in this phase of sleep, we have more dreams during REM than all the other different stages combined. We're also much more likely to wake up during this phase, which is why we sometimes remember our absurd REM dreams.
Cannabis And REM
There's plenty of anecdotal evidence suggesting that regular cannabis users have fewer dreams, although the science behind this is still very patchy. Still, it's common for the Sandman to stop visiting those who smoke large amounts, with frequent users claiming they don't dream at all.
Of course, this phenomenon may be partially explained by the fact that cannabis is such an effective sleep aid that users simply don't wake up during REM sleep and, therefore, can't remember their dreams. However, one study conducted in 2019 found that frequent cannabis users actually have shorter periods of REM sleep per night than non-users[I].
Study participants wore headbands that recorded their brain activity as they slept for two consecutive nights. They were also instructed to set an alarm to wake them at various points each night so that they could write down any dreams they may have experienced in a dream diary. Compared to non-users, cannabis smokers exhibited a longer sleep latency – meaning it took them longer to nod off each night – and shorter REM sleep.
All of the smokers in the study regularly used cannabis strains containing tetrahydrocannabinol (THC), leading the study authors to speculate that the cannabinoid may decrease REM sleep and therefore stop people from dreaming. In spite of this finding, however, the researchers wrote that "cannabis users reported higher bizarreness in their dreams," so it's fair to say the study's findings are less than straightforward.
What Happens If You Quit Cannabis?
Another phenomenon that hasn't received enough clinical attention is known as REM rebound. With no real studies and few corroborated facts regarding this subject, we must once again rely primarily on anecdotal evidence. However, given that so many cannabis users report the exact same thing, it seems almost certain that REM rebound is legit.
Essentially, this occurs when a frequent user takes a break from cannabis. According to reports, those who experience a reduction in dreaming while using suddenly start having more dreams once they stop. These dreams are often much more vivid and intense than your average nocturnal hallucination, and it's also common for people to have more nightmares when they're undergoing REM rebound.
It's thought that this effect is caused by the brain 'catching up' on all the REM sleep it missed out on previously. This means that when THC ingestion ceases, the amount of time spent in the REM stage suddenly increases, resulting in more vibrant dreams.
What About Other Cannabinoids?
Cannabis affects the brain and central nervous via the actions of many different chemical components, including cannabinoids and terpenes. After THC, the most famous compound in cannabis is cannabidiol (CDB), which is also considered an effective sleeping aid.
Unfortunately, CBD's impact on dreaming is yet another understudied subject, which means that we must once again rely on anecdotal evidence. For instance, many users report more vivid dreams and even lucid dreams after using CBD. Lucid dreams are those in which the dreamer is fully aware that they are dreaming and can often control what happens in the dream – which is obviously pretty awesome!
Regarding the different stages of sleep, a small amount of research suggests that CBD may influence the sleep cycle in a dose-dependent manner. More specifically, it has been shown that high doses of CBD might lead to more REM sleep, while low-to-moderate doses have the opposite effect. However, much more research is required to confirm this.
So, Are The Effects Of Cannabis Good Or Bad?
Any sleep expert will tell you that REM is essential for mental health and cognitive function, so reducing the time spent in this phase obviously has the potential to be detrimental. According to Dr Matthew Walker from the Center for Human Sleep Science, REM dreams allow us to process emotionally charged events and memories since this stage of the sleep cycle represents the only time when noradrenaline – a chemical linked to anxiety – is markedly reduced throughout the brain[ii].
He also says that REM sleep boosts creative thinking, memory and general cognition. That being the case, the prospect of reducing REM via the use of THC doesn't sound great.
At the same time, though, sleep deprivation and low-quality sleep are also known to negatively impact mood and cognition. Given that THC and other cannabinoids help those with sleep problems to get sufficient shut-eye, it seems that the situation isn't entirely black and white, and a balancing act is required to get the maximum benefit from cannabis: those who frequently use should try to avoid cycling between periods of reduced dreams and REM rebound.
It's also worth noting that reduced dreaming may be a positive thing in some cases. Those suffering from post-traumatic stress disorder (PTSD), for instance, may find that cannabis helps eliminate nightmares and other disturbing sleep experiences.
Overall, then, it's pretty clear that cannabis has a significant effect on dreaming, although whether this is a good thing or a bad thing depends on the needs of each individual.
[i] Bradshaw C, Borcsok R, Taylor M, et alP039 REM sleep and dream reports in frequent cannabis versus non-cannabis users, BMJ Open Respiratory Research 2019;6 - https://bmjopenrespres.bmj.com/content/6/Suppl_1/A23.1.citation-tools
[ii] https://greatergood.berkeley.edu/article/item/why_your_brain_needs_to_dream
