I watched a neuroscientist talking about this quite recently, when the brain is stoned it skips REM sleep which is when you would dream, normally about 4 hours in you fall into this deeper sleep state, without it you can sleep for 8 hours but still feel quite tired and like you need more sleep. It's because the brain hasn't been able to enter REM sleep. And when you stop smoking weed, the brain has to catch up with all the missed REM sleep, so if you've been smoking for 5 years consistently, and stop smoking it you can have really intense dreams for like 6 months (i dont think that's the actual figure i am just giving an example).

I think dreams play important roles spiritually and mentally, they may seem random but it is clearly some sort of filtering process the brain needs. There are 1000's of things a day you don't consciously notice because your brain doesnt want to overwhelm you, so anything not relevant to the task at hand it doesnt bring to your conscious attention. I guess it needs to do something with that information, kinda like when you have to clear the memory on your phone or laptop for optimal functioning, they can get a bit sluggish if you don't. So it won't be like that for ever, it will die down, it's just your brain going through an intense backlog of unfiltered crap. I think somehow during this process the brain is in an altered state like when you open up a pc on safe mode, and in this state there could be spiritual links too. This second bit is just what i think not what that guy said.

This was about 2 months ago i watched it, so not ages ago but i may have a few inaccuracies which i apologise for, but worth looking into if you're struggling with it. Sometimes understanding the process is helpful.