here is my take:

I had the same exact question and condition. however I took a psychology class and figured it in there

u have REM sleep and Non-rem sleep. most of the remembered dreams occur in Non-rem sleep. REM sleep is mostly where body really relaxes and rapid eye movements occur

i know science has not reached a conclusion on this yet, but my theory is that when u smoke weed, the chemicals in your system either turn your entire sleep into REM (normally 20-25% of sleep time is REM) or u do go through cycles, but the effect on short term memory makes it almost impossible for us to remember any of the dreams, while they have been taking place.

I have quite a different feeling all over my body when i wake up after a smoking before sleep
than sober

and i think whats needed to affect the brain n body in such a way is in the bloodstream and body even without immediate smoking before sleep if the person is a regular smoker, it only takes a tiny amount which can circulate/be stored for a while in the body

just what I think, its merely a hypothesis that must be proven