According to Leafly, a change in a marijuana user’s routine can lead to more frequent, vivid, or lucid dreams.
Cannabis and REM Rebound Theories
Not long ago, I took a 3-week tolerance break from cannabis. I normally don’t dream much at all, and when I do, they’re typically unremarkable and unmemorable. But a few days into my t-break, I had vivid dreams involving herds of unicorns, a sky full of red balloons, a backdrop of exploding volcanoes, and the disembodied, narrating voice of Tommy Wiseau. It was so vivid that I expected to wake up in this strange apocalypse, only to find myself back in a drab reality devoid of unicorns and balloon-filled skies.
I did some reading on cannabis and sleep afterward to see what might have spurred these unusual dreams and found a 2008 review that correlated cannabis consumption with decreased REM sleep. Logically, that would suggest that cannabis abstinence can trigger “REM rebound,” or a sudden increase in REM sleep and dreaming. This rebound phenomenon was observed in a 1975 sleep study and again in a 2008 PSG study. Another small 2004 study identified decreased REM duration in subjects dosed with 15mg of THC as well as a THC/CBD mixture, but did not record the effects of cannabis cessation.
Though more research is needed to really substantiate this link between cannabis and REM sleep, it would seem this is the likely explanation for why some have strange dreams after quitting.