I have had those sort of experiences as well..many times. It always seems to happen late at night after I have slept for at least an hour or 2..I will wake up in my bed, in the dark, into a state resembling an extremely clear and vivid ayahuasca peak..I can see the grids and everything. On a few occasions I then started to expand and leave my body and enter the lives of other, seemingly random people. I lived through them, and was them. I had no idea who these people were. At times i would reabsorb into this thing that was like a net of energy, connecting all of us..then I would focus in on some other soul making up this net and enter into them and have the experience of being them..it is really really strange. I wish I knew what neurotransmitters are playing a role here, but I would suspect melatonin, pinoline and 5meo DMT at least, prob alongside a bunch of others..to bad I cant do it at will.

I also had one other experience where I was taken abord a ship by a race of humans from another world. All I can think of is that I had lots of cacao that day. I fell asleap late at night on my couch, and the next thing I know I am leaving my body and boarding this ship with these beings. They were very kind to me and took me way off into another galaxy..where exactly I cant recall. They were explaining to me all this complex stuff about how they were once connected to us, like we came from the same world. Long ago there was some event or something, Im not sure really, but it split us and now they live off in this other galaxy, or maybe it was another dimension..but the showed me how our worlds are somehow comming back together..they are far far more advanced technologically than we are, and also have tremendous shamanic technologies..they said the mayans and other cultures had ways of communicating with them. They are like our brothers and sisters from the past and care greatly about us and want us to thrive and save our world as they have done. They're world is like an eden now, as they were able to develope sustainable technologies that worked parallell to the natural environment, as opposed to against it. Alot went on that I couldnt recall when I got back..they brough me back to my sleeping body and I snapped up on my couch in the dark, awake. I sat there for about a good hour just freaking blown away. It was sooooooo real..unlike normal dreams I have..

There are definatily some weird neurotransmitters released at certain times at night..what conditions facilitate them etc I am not sure..

BTW..I was really into astral projection, lucid dreaming and meditation way before I tried any psychedelic because my mother had all these books on this stuff..she used to talk to me and show me these robert monroe books all the time..maybe that plays some role..I have always had natural sleep paralysis, projection and lucid dreams..and still do to this day.

Its like being dipped into universal consciousness, one second im a person closing my eyes falling asleep, then i see the fractal kaleidescope patterns...
From subjective experience i would say that for sure no doubt DMT is released endogenously in between these three states, and smoking DMT can effect its release during these states. Im not saying whether that's a good thing or a bad thing as my experience of it has gone either way, just reporting.

I had a dream last night that I sniffed yopo with a shaman. It was a very enlightening experience. I think it happened because this topic was fresh on my mind so I tried to explore the possibility of inducing endogenous DMT on myself. I sure did feel like I was tripping.