I agree with purple_cloud. Whenever I smoke within a few hours before bedtime I can't seem to remember my dreams. I have speculated that remembering dreams is dependent on waking up in a certain cycle of sleep related to the dream. I think this because Cannabis usually helps me sleep deeply throughout the night, or at least without waking up, and it also makes me forget my dreams. Also, the opposite could also be true, as I have read somewhere that marijuana was observed to disturb REM sleep and other deeper sleep cycles. As these states of sleep are often associated with dreaming, perhaps this supposed inability to enter said states is responsible for my inability to remember dream sequences as clearly as I do sleeping sober.
But these are just some ideas, I won't pretend that I know they are at all correct. Everyone reacts differently, and I don't doubt that your friend has been having vivid dreams. But from what I have gathered from myself and others, smoking marijuana usually has the opposite effect on dreaming. Perhaps it is due to some recent emotional stress... that is what usually gives me "bad dreams" especially when I was a young-un.
