According to the National Academy of Sciences, marijuana use also has negative impact on REM sleep (by 49%).
I'll testify to that! I've been an everyday toker(rarely dream, or I should say remember dreams) for a few years until this january when I picked up a new job away from home for 3 weeks at a time. I decided to challenge myself to not toke up for those 3 weeks.
It took about a week of not smoking until every night I was having all kinds of awesome dreams, I think my body was like pheew I can finally sort all this shit out from the last few years, nothing deep but you know your dreams and r.e.m sleep are kinda like the de-frag part of a comp.
Another plus was once I got home and smoked a big fattie, the high was unlike ever before it was kinda all new, fresh and refreshing.