I wrote about this a long time ago in some comments here- I'm not sure where or when- but there seemed to be a lot of interest in it. Because of this, I thought I would share the post I've written about it here. 

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I also once had a dream that was a whole lifetime long. Waking up from it was disorienting and came with a deep sense of loss. But I didn't talk to anyone about it afterwards and I've now forgotten all of the details.

I knew someone in college who also had this experience. Said she had a whole life with husband and kids, IIRC, and then woke up.

The problem with these dreams is that you don't experience an entire life; more precisely, what you experience is simply your recall of a memory remembering having experienced an entire life. What I think happens is that you are suffering from an Boltzmann brain/Omphalos-style skeptical paradox in real life, where your brain jumps directly to the final memory 'I lived an entire life' without all, or even any, of that living actually happening - sort of like a speedrunner glitching a game to jump to the 'The End' screen, or the same way that you feel you have Insights™ while on psychedelics, while in reality, all that is happening is you feel you have the feeling of having an insight yoked to an arbitrary statement like 'a smell of turpentine pervades throughout' (which can be false).

(This might seem like a fairly exotic thing to do, but brains do a lot of weird things, dreams jump around like crazy and often seem to skip beginnings to start in media res (thus often near endings), and given all the reinforcement learning the brain is doing, a special focus on endings/outcomes would not be surprising, especially as that sort of episode-level learning seems to be one of the best functional explanations for what dreams do.)

That seems fairly consistent with what happened to me. I did not experience my entire life in the dream- just the swim meet and the aftermath, and my memories were things I just summoned in the moment, like just coming up with small pieces of a story in real time. The thing that disturbed me the most wasn't living another life- though that was disturbing enough- but the fact that a character in the dream knew a truth that "I" did not. 

Who knows, maybe it was your right hemisphere. 

 

Shout-outs to them, if so. Almost definitely the first time someone has directly referred to them, that's got to be very exciting. 

 

Even if you are not literally their right hemisphere (not like you would know of course), but if you are there and if you have access to high-level knowledge of the world: hi, good job all of these years! 

Thanks for the link to the paper on a functional explanation of what dreams do! Do you, by any chance, have more recommendations on what to read on this?

I’ve had fuzzy intuitions that dreams might have something to do with using collected episodes to imagine new ones and do some sort of learning on those (eg maybe improving heuristics/making them more coherent with others/the knowledge or something), but I haven’t properly thought about this or even googled what do people already know, and would be pretty curious if there’s a good collection of links

The usual RL approach to dreams is to treat them as either a kind of exploration (not necessarily model-based, possibly just chopping up memories of episodes to stitch together or doing something intermediate like a successor representation) or focus on the hippocampus which appears to encode spatial representations of memories (which makes sense given agents are embodied and typically must move through space to accomplish anything, as opposed to extremely unnatural behaviors like sitting at a computer all day*) & then be doing something akin to experience-replay to finetune itself.

Maybe look through https://www.reddit.com/r/reinforcementlearning/search?q=flair%3APsych&restrict_sr=on&include_over_18=on&sort=relevance&t=all

* You ever notice how rarely dreams are about computers or smartphones? When I kept a dream journal, I was bemused at how completely unrepresentative of my life it was, primarily in omitting computers; my dreams had plenty of time for all sorts of other boring stuff, like going to school having forgotten to do my homework the night before, however... It's a bit like how fiction struggles to incorporate computers at all. "Here is our contemporary protagonist who spends 10 hours a day on her computer and/or tablet and/or smartphone. Let's, uh, have her lose it in the first 10 minutes so we can get the plot going."

Weirdly enough I dream tons about my phone and laptop. It’s usually how I know if I fell asleep or not(while napping during the day). Do I remember looking at my phone or not.

Wow.

Not sure what else to say.

(Edited to add: other than that I've heard a few people report something like this, and it weirds me out each time.)

Yeah- the experience really shook me. I'm prone to fairly vivid and interesting dreams, but this was definitely the strangest. 

At least twice in my life, I have gotten a crush on someone, only to wake up and realize that the woman I had been pining after literally did not exist. One of the times, the dream person was quite similar to someone I knew irl (metaphorically, not visually) but the other time it was not.

I've gotten a crush on a fake person from my dreams about 4 times. It was all the same girl that just randomly appeared in 4 of my dreams (they weren't like erotic or anything, just normal dreams)

I can relate. I also had a dream in which I suspected I was dreaming, attempted to do some tests to rule that out, ruled it out to my satisfaction, and later woke up from it. Disconcerting.

Is there any data on how prevalent this is? I only occasionally experience a dream from the perspective of someone straightforwardly analogous to myself.

A number of spiritual traditions have their most advanced practices in dream realms.

https://en.m.wikipedia.org/wiki/Dream_yoga

Note the part where it says that it’s usually passed on by a teacher. It’s entirely possible to meet this teacher in your dream; in your case, the coach.

This happened to me several times when I was a tween, and I came up with the light switch trick. I realized that in dreams the lights are all dimmers, the light never switches instantly from off to on. So when I wondered if I was in a dream I looked for a light switch.

I have a similar trick I use with pirouettes- if I can turn and turn without stopping, then it is a dream. Of course, in this dream, I was not a dancer and had never danced, so I didn't even think of it.