I can say smoking helped me sleep so much I forgot if I had or not a dream at all to the point I got fixed trying to remember then forcing dreams now I manipulate them, I really think it's practice just like any other thing, if you've had a full day of work, kids, SO, friends, tv, daily habits and such in my case I won't dream much... days off, meditation, imagination, art, music, visual stimulation such as parks, body's of water, sun sets seem to really help with dreaming, not sure, but I have my own thoughts as to why, I think the key is being the individuals reaching enlightenment and in that can control not only the consciousness but also the subconsciousness...