THC reduces the intensity of rapid eye movement (REM) sleep by up to 40%, even at low doses, by altering nocturnal brain electrical activity.

noli's read

REM sleep is a crucial phase for emotional regulation and memory consolidation, and research indeed confirms its alteration by cannabinoids. Studies, notably systematic reviews published in 'Sleep Medicine Reviews', indicate that THC decreases total REM sleep duration and can reduce its electroencephalographic intensity. It is common to observe REM sleep suppression in regular users, often followed by a 'rebound' effect (nightmares or intense dreams) upon cessation. While the 40% figure may vary by individual, the general trend of a reduction in this phase is well-documented in scientific literature. The claim is therefore supported by consistent observational and experimental evidence. It is not an exaggeration, but a recognized clinical observation regarding sleep architecture.

the sources

No named source held this one up — that absence is part of the verdict.