It's true. Though scientists haven't figured out the reason for dreaming, if you don't dream you die. There was this video I saw a while back about this guy who couldn't physically experience REM sleep, which is where the most vivid dreams occur, and eventually he was hospitalized and died within a few months. I suppose it would seem like we don't dream when we smoke pot because it messes with our memories. I mean it's hard enough just to remember a dream sober but to remember a dream after a night of smoking....well that's just madness!