Many people who smoke marijuana report having no dreams, yet after they quit, the same people report extremely vivid and intense dreams. Most vivid dreams take place during REM sleep, so the logical scientific question is “Does marijuana (THC) affect REM sleep?” A study conducted in 1975 compared the sleep patterns of experienced marijuana users with non-smokers. The results showed reduced eye movement activity and less REM sleep in the THC condition. They also reported a REM rebound effect, which is more REM activity upon withdrawal from THC. Scientific evidence exists that correlates marijuana use with a loss of REM sleep and dreams, so the next time you smoke marijuana and don’t remember your dreams you will know why.