Scientists Link Cannabis to REM Suppression and 72% Higher Dementia Risk in Severe Cases
Updated
Updated · The Washington Post · Jul 23
Scientists Link Cannabis to REM Suppression and 72% Higher Dementia Risk in Severe Cases
3 articles · Updated · The Washington Post · Jul 23
Summary
Roughly 9% of U.S. adults use cannabis as a sleep aid, even as newer research shows THC can alter sleep architecture, suppress REM sleep and reduce dreaming.
Laboratory studies suggest THC may help people fall asleep faster, but objective measures have generally found worse sleep quality and more awakenings despite users reporting better rest.
Researchers say chronic THC exposure changes the brain’s endocannabinoid receptors; when use stops, that disruption can trigger insomnia and a REM rebound marked by unusually vivid or distressing dreams.
A 2015 placebo-controlled study in soldiers with severe PTSD found a synthetic THC analogue reduced nightmares, showing the drug can reshape dream content as well as sleep stages.
Long-term risks remain unsettled, but a 2025 JAMA Neurology study of more than 6 million adults linked cannabis use severe enough for hospital or emergency care to a 72% higher five-year dementia risk.
Science says cannabis harms sleep, but users feel rested. What does this paradox reveal about our brain's perception versus reality?
Quitting cannabis triggers a 'dream rebound.' Is this intense phenomenon a dangerous side effect or a necessary neurological reset?
2025 Canadian Research Finds 72% Increased Dementia Risk After Severe Cannabis Use in Older Adults
Overview
Recent research from a large Canadian study involving over six million adults aged 45 and older has raised concerns about a link between severe cannabis use and a higher risk of dementia. The study tracked participants with no prior dementia history and found an association between heavy cannabis use and increased dementia risk. However, experts caution that this does not prove cannabis directly causes dementia, highlighting the complexity of the issue and the need for more research. These findings contribute to ongoing discussions about the long-term effects of cannabis on brain health, especially as use increases among older adults.