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People with cannabis use disorder reported poorer sleep quality and did worse on
memory tests.

As Dallas residents consider a November ballot measure to decriminalize small amounts of marijuana, new
research is shedding light on the drug’s impact on sleep and memory.
In a recent study published in The American Journal of Drug and Alcohol Abuse, researchers at the University of
Texas at Dallas found that adults with cannabis use disorder tended to experience poorer sleep than others. They
also performed worse on tests assessing visuospatial memory, or the ability to retain and process information about
an object’s appearance and location.

“What this paper does is provide a bridge between the two things and helps establish that perhaps some of the
memory impairment associated with cannabis use is indeed due to poor sleep quality,” said Christopher Verrico, an
associate professor of psychiatry research at Baylor College of Medicine, who was not involved in the study.
The study also underscores the many unknowns of marijuana’s impact on the human body and the need to be
cautious when using it, said Ashley Garling, a clinical assistant professor at the University of Texas at Austin
College of Pharmacy who also was not involved in the study.

In a 2022 survey of more than 27,000 people between ages 16 and 65 in the U.S. and Canada, almost half reported
using cannabis to help with sleep. In another survey, commissioned by the American Academy of Sleep Medicine in
2023, a quarter of Americans reported occasionally or regularly using pot to help them stay or fall asleep. Andparents with children under 18 living at home were more likely than nonparents to use marijuana as a sleep aid —
30% versus 19% 

Whether marijuana actually helps people fall asleep isn’t clear. Some studies and surveys suggest it doesn’t improve
sleep, while others suggest it might, particularly in people with conditions that interfere with sleep like chronic
pain.
Additionally, the two main active ingredients in marijuana — delta-9-tetrahydrocannabinol (THC), a psychoactive
chemical that makes users feel high, and the nonpsychoactive cannabidiol (CBD) — influence sleep in different
ways. Low doses of THC may improve sleep while higher doses may disrupt it. The opposite is true for CBD.
Studies have shown that long-term marijuana use can impair cognitive function depending on the age someone
starts using. A 2016 study tracking over 3,000 middle-age adults over two decades found that for those who used
pot for more than five years, their verbal memory was worse compared with those who used marijuana less often. A
2018 study found that young people who used marijuana frequently were more likely to score slightly lower on
memory tests and not do as well at learning new information and higher-level problem-solving compared to their
non-using peers. A separate 2018 study found cognitive performance among young cannabis users improved when
they stopped using it.
But studying marijuana’s effect on both memory and sleep had not been done before, said Francesca Filbey,
director of the University of Texas at Dallas’ Cognitive Neuroscience Laboratory of Addictive Disorders, who led the
new study.

To answer that, Filbey and Tracy Brown, the study’s first author and a doctoral student at the University of Texas at
Dallas, surveyed more than 200 people from Dallas and the Netherlands about their sleep quality in the previous
week. Of the respondents, 141 had cannabis use disorder, a condition marked by a dependency on marijuana that
affects 3 in 10 people who use it; the other 87 had used marijuana in the past but not as frequently and not within
the three months prior to the study.
Those with cannabis use disorder reported more sleep problems compared with the other group. They also tended
to perform not as well on tests assessing their visuospatial memory.
While this finding indirectly ties marijuana use to memory, Brown said there is likely an underlying mechanism:
the endocannabinoid system, a recently discovered signaling network that regulates sleep, learning and memory,
among other functions. Cannabinoids, the chemicals at the heart of this system, are produced naturally by our
bodies and are found in marijuana.
“What we know about the endocannabinoid system is that it’s a regulatory process within its own right, but it
signals circadian rhythms, our sleep-wake cycles,” said Brown, with some hormones spiking in the morning and
others falling in the evening. He added that sleep is crucial for the brain’s ability to consolidate new information
into memories.
The next step to exploring marijuana’s impact on sleep and memory will be to study brain activity during sleep to
gauge how restorative it is in real time. Future studies will need to investigate how differing amounts of THC and
CBD in the body affect sleep and memory, said Garling of UT Austin, who added that the amounts vary based on
how cannabis is consumed. How biological sex affects the interplay of marijuana, sleep and memory will also need to be considered because
this study had more male participants than female. Studies looking at long-term cannabis use have found that sleep
in women is impacted at a higher rate compared with men.
Filbey and Brown emphasized that the study is just the first step to a better understanding of how cannabis impacts
the brain and that more studies are needed, given the public health concern posed by its widespread acceptance.
“With any type of medication, you have all these different clinical trials. But [with] cannabis, it’s putting the cart
before the horse,” Brown said. “We’re legalizing it, not necessarily at the federal level but the state level, for
medicinal and recreational [use]. But the fact that it’s being legalized for medicinal use is informing people that this
is something safe or effective. We don’t have that kind of research yet.” Under federal law, marijuana is classified as a Schedule I drug, with a high risk of abuse and no legal use. Though
exceptions can be made with permission from the Drug Enforcement Agency, this classification has posed a
significant roadblock for clinical research, Filbey said. But she is optimistic that will soon change. In April, the DEA
announced that it would consider bumping marijuana down to a Schedule III drug. It would remain a controlled
substance, but the move would acknowledge its potential medical uses and make research easier.
Medicinal marijuana in Texas is legal only for people with conditions including severe epilepsy, autism, cancer and
PTSD. Outside of those conditions, cannabis use and possession continues to be penalized. 

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