> I occasionally have lucid dreams, where I realize I'm dreaming. When that happens, I can take control of the dream and do cool things

I experience lucid dreams I can control quite frequently. The thing I do most often is let the dream play out, but go back in (dream) time to replay certain scenes differently if I'm not happy with the outcome.

It's really pretty cool - like being in some kind of super-advanced VR simulation, or under the influence of some impossible drug. If anyone ever figures out tech to make this just happen (kind of like simulation VR goggles in scifi films), they are going to be very, very rich.

In another kind of "weakly lucid" dream type I know I'm dreaming but I don't have (full) control. So I can't make people answer what I want, but it feels like I can "mentally manipulate" them and push their answer to a certain direction, like make an attacker friendlier or so.

Dreams made a whole lot more sense to me when I learnt about idea of the brain as a predictive processing machine. It asserts that the brain works as a sort of recursive two-sided process, with theory creation on one side and evidence collecting on the other. Recursive in that the visual processing system might get a "is that a door?" theory from a higher level system, which it'll then answer by collecting and trying to match evidence from multiple lower level systems ("is that an edge?" "is that a shadow?" etc.) until it eventually reaches the level of processing stimuli directly, with each system on the way acting as both questioner and answerer.

In this framework dreaming is when the evidence collecting side becomes a lot less rigorous than it usually is, so it says "sure, why not" without reference to a stimulus (i.e. a way to be falsified). In other words it's the brain's predictions continuously coming true.

One theory I had read a longtime ago was that nightmares were a way for the subconscious mind to wake-up the conscious mind.