Marijuana and Morpheus: Why does pausing cannabis use spark vivid dreams?

Experts explain why drugs like THC and CBD in cannabis can alter how our memory and REM sleep function

Published October 28, 2023 1:59PM (EDT)

Woman sleeping peaceful on cloud (Getty Images/urbazon)
Woman sleeping peaceful on cloud (Getty Images/urbazon)

In a dream that has stuck with him long after waking, Eric was caught in the middle of a flood. As he helplessly watched the water rise around him, he felt an overwhelming sensation of panic. He tried to find his wife while dodging debris and fragmented pieces of glaciers around him, but he had the sinking sensation that he was experiencing his imminent demise. At last, he found her, and a deep calm washed over him. He no longer worried about the rising waters surrounding him — he was at peace with death.

Eric, who asked to be referred to by only his first name, attributes the vivid dream to not smoking marijuana, which he does habitually. In periods when he is smoking, he rarely remembers any of his dreams. But once he stops, the dreams come back more frequently and in more detail.

“When I'm not using, I will always remember more dreams,” Eric told Salon in an email. “Not every night, but definitely more often, and the memories are more vivid.”

This is a common phenomenon involved in marijuana cessation, said Dr. Ryan Vandrey, a professor in the department of psychiatry and behavioral sciences at John Hopkins School of Medicine. Many people, including Eric, use marijuana in part to help them fall asleep. While some evidence suggests that marijuana may help with the onset of sleep, there are still some unknowns around its impact on the quality of sleep.

What is known is that the main intoxicating ingredient in marijuana, THC, (tetrahydrocannabinol) is associated with decreases in rapid eye movement (REM) and increased slow wave sleep. However, another chemical in cannabis, CBD (cannabidiol) is associated with either increases or decreases in REM, depending on the dose. Many of these studies are in animals, not humans, and the ratio of THC to CBD in marijuana can differ significantly from product to product — not to mention the wealth of other sleep-impacting cannabinoids like CBN — so it's not easy to tease out what's really going on.

Regardless, REM is critical to the whole architecture of dreaming. Typically, if you wake up during this stage of sleep, you’ll be able to remember your dreams. It follows that reduced REM sleep leads to a lesser chance of remembering your dreams.

But when people using marijuana develop a tolerance to it — meaning they smoke regularly for weeks, months or even years — and then stop using it, the body can have withdrawal effects that behave opposite to typical use of the drug. That means, during the withdrawal period, people who stop using marijuana may take longer to fall asleep, have more REM sleep and have more memorable dreams that reemerge more intensely and vividly.

There could be some memory-impairing effect of THC that suppresses dream recall, which bounces back with a vengeance once people stop using it.

“As with most drugs, whatever the drug does, as soon as you take that drug away, there’s the opposite effect,” said Margaret Haney, Ph.D., the Director of the Cannabis Research Laboratory at Columbia Psychiatry. “The REM is no longer depressed, and it rebounds. We suspect that is why people report intense dreams because they're probably having more REM than the average person during their sleep.”

While most symptoms of cannabis withdrawal, including not being able to fall asleep, changes in appetite and anxiety, tend to go away within a few weeks, the effects on dreaming occur on the day people stop smoking and can last for up to 45 days.

In addition to changes in REM, Vandrey said there could also be some memory-impairing effect of THC that suppresses dream recall, which bounces back with a vengeance once people stop using it.

“When you stop using it, that goes away and the recollection of dreams is there and restored,” he told Salon in a phone interview. “For someone who's been a daily, habitual user for years and years, the sudden recall of dreams, especially in a vivid way, is shocking and very notable.”

Sleep medicine physicians typically only recommend sleep agents in the short term in order to avoid dependency. Long term use of marijuana can also develop a dependency that impacts sleep. It’s still unclear to what extent changes in REM and other aspects of sleep — in what is sometimes called “sleep architecture” — caused by THC use are affecting overall health.

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“That medication is only going to be effective until it's not, and we know that when people develop tolerance to the sleep-promoting effects of THC, that long-term heavy use can lead to this withdrawal effect,” Vandrey said. “That's the concern.”

Because of the challenges and restrictions on studying marijuana, which is a Schedule I substance still illegal in 27 states, it’s still unclear whether there’s certain dosing that enriches sleep or deteriorates it, how smoking versus eating edibles changes sleep or whether any effects can be mitigated with using combinations of THC and CBD) The fact that many CBD products on the market have small amounts of THC and vice versa further complicates things.  

Moreover, many studies examining cannabis and dreaming were done in the 1970s, and the cannabis landscape has changed drastically since then, said Dr. Timothy Roehrs, a psychiatry professor who studies the effects of drugs on sleep at Wayne State University. Far more research has been conducted on the effects of sleep on alcohol, which operates differently on the brain and body but does seem to reduce REM sleep in high doses and is thought to change sleep architecture.

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THC is lipophilic, meaning it binds to fat molecules and can stay in the body for up to 30 days as it is slowly released in the blood stream. As Roehrs explained: “There are a lot of factors that can be affecting the amount of THC in your body at any given time.”

Although some marijuana brands might promote its effects on sleep, the jury’s still out on whether that’s true. Its effects on dreaming certainly indicate it’s disturbing at least some aspects of the process.

“People are making decisions about using it for medical reasons based on very, very, little data — and a whole lot of marketing,” Haney told Salon in a phone interview. “Right now, we don't have the information we have for every other medicine.”

By Elizabeth Hlavinka

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Cannabis Cbd Cbn Dreaming Dreams Health Marijuana Sleep Thc