The DreamBank, a collection of over 20k dream reports

1. I forget to take my mask when I leave my apartment. Apparently the door man doesn't notice.

2. When I try to go back to my apartment to retrieve my mask, the door man doesn't let me in, because you need a mask to enter.

3. I'm not allowed to enter any stores to buy a mask, because you need a mask to enter.

So I'm trapped outside in this catch-22.

for most of my life i never really thought much about how dreams work. i shared the same notion with most people, that they are a kind of sloppy simulation of real life. but it always stuck in my mind that this didnt make any sense: the physics of life are too complicated for the brain to simulate in real time in a way that recreates sensory inputs. and why would the brain have hardware that was dedicated to performing dream simulations? wouldnt that be rather a lot of hardware and energy for no apparent reason? but i always chalked it up as one of the great mysteries of our time and didnt dwell on it. and then the answer came to me.

it is well known that it is possible to "lucid dream." i have experienced this, and it is what precipitated my effort to understand dreams.

the answer is that the brain works with abstractions, it stores everything in the world, physical objects as well as feelings and concepts, as a kind of model that can be recalled. as you experience more things, the library of abstractions grows larger.

you are a small part of your brain. there is a part of the brain that holds a "simulation." this is your consciousness, you live inside this simulation, everything you experience is inside this simulation. it is a simulation of the physical world, but it contains much more than physical objects. it contains mental "primitives" that inform your emotions, your identity and your feelings about the world and your place in it. the non-physical aspect of the simulation might be called the "ego" and people who experience so-called ego-death are actually experiencing the simulation with these things taken out of it. at the core of the simulation is some kind of atomic, immutable "self" that is discreet and separate from all experiences, traumas and emotions. so to make it short, your being lives inside a simulation where the physical world is simulated as well as you as a person.

there are other parts of your brain that manage the simulation. some parts of the brain create new abstractions from sensory data. other parts of your brain monitor sensory data looking for things that it recognizes, looking for abstractions that have already been created. and another part of your brain is responsible for placing those abstractions into your simulation when they have been found in the environment. when the abstraction is placed into the simulation, you experience it. your brain is constantly monitoring reality through sensory data and recreating it in your brain-simulation using "assets" that already exist, assuming there is nothing too new in your environment. it is possible for this machinery to break, which is what we call a hallucination. a hallucination is not the creation of something that doesnt exist, it is the mistaken placing of a pre-existing asset into the simulation. objects are a composite of many different abstractions, and this is why hallucinations can have strange, ethereal or other-worldly qualities. a human figure can be placed into your simulation without the concept of humanity accompanying it, or the presence of a person can be placed without a physical manifestation. all kinds of weird things are possible. the takeaway is that the simulated world that is created for you by your brain is very sophisticated, hard to get right, and the symphony of neural mechanisms to make it all work is probably breathtakingly complex.

why? its an optimization. experiencing raw sensory data is too inefficient. the scope within which you make decisions must be narrowed. and this leads into the answer to dreams: there are other optimizations at play. there is yet another part of your brain that actually looks inward at the simulation and the assets that have been placed within it. it will then guess what other assets should be in the simulation based on experience, and place those assets into the simulation. these guesses assets are the same as any other assets, of course. their presence in the simulation is the same as anything else. they are just as real, in every way, in your experience, as anything else. this optimization probably saves time and energy, saving the brain from going through the long process of interpreting every bit of sensory data and matching it to pre-existing assets. instead, your brain translates the big things and your brain guesses everything else.

when you take this entire system into account, and you take away all sensory input, what do you get?

you get a dream.

what happens when you keep certain parts of the cortex active during sleep? you get a lucid dream.

what happens when you consider the situation where a little sensory input leaks into the brain during sleep? you get a simulation loosely guided by sensory data, just as we all have experienced.

dreams are in reality not simulations but a demonstration of the awesome power of the guessing machinery of the brain. it is not a sloppy simulation, but incredibly good guessing.

the reality you experience in a lucid dream is exactly the same reality you experience when you are awake. dreams are reality with sensory decoupling.

most of the things you experience in your life are guesses. most of the things that you are aware of at any given moment are just guesses. the guessing is so good that it has gone unnoticed.

because the brain uses a fundamental model of abstraction, many parts of life are consolidated, in part, into an abstraction and therefore are very localized in space in the brain. the amount of accuracy and control we will have over matters of the mind with simple electrodes ala neuralink will be much higher than anyone understands.