Where does the light come from in a dream or even a memory?

It is all virtual. A simulation. Your brain creates the lights. It creates the world. It creates everything.

Are you suggesting we never really see light in the first place?

Your brain constructs a virtual model of reality based on electrical signals supplied by your sensory organs.
People do not even see colours the same.
https://www.youtube.com/watch?v=MJBfn07gZ30

True dat ^
The light, colors, details, it is all stuff your brain has processed before, so simulation is just simple as running the codes through without outside sources.

And you are all sure there is no microlight emitter “painting” the main optical feed with actual light, like a very sophisticated cartoonist?

You mean like in a movie theater?? Who, exactly, would be running the show??

Listen, I don’t have the answers..

I am hypothesizing: Anything we see, anytime we see it, is directly coming from a light source.

That is the task of your eyes. Your brain is simply reading the codes sent from your eyes to present to you as “comprehension”. Your brain doesn’t see anything, ever. Your eyes see, and your brain takes the information presented by your eyes, and categorizes the information so that you have reference to consult in an ongoing basis. If your brain did not do that for you, every single thing would be new to you, every single time you encounter them. You would never know what is dangerous, or delicious, or cold.
Your eyes see light, and color, and sends signals to your brain for indexing. Many many things are cross indexed, so we know the difference between ketchup, and a red ball, or a car.
Sometimes memories are nothing more than your brain trying to sort out whether this item goes with that outcome, or not.
Dreaming is brain’s best chance to mess around with colors, textures, tastes, and such, and work through outcome potential, so the files stay fresh, and accurate. There only seems to be light, because brain happens to have some vision files open and active at the moment. It is nothing more that codes, much like the Matrix movies approach the subject of perception. If a someone else’s file system from their brain entered your brain’s files, you would suddenly be perceiving same old stuff in confusing new ways. See Jumanji, the remake, or any Freaky Friday movie.
In each case, the perception of others compared laterally with our own is at play in the story.

Light and color in dreams or memories have no more to do with actual illumination than dreaming about a delicious meal would fill your empty stomach.
K?

What you want to do is read up on some research involving studies on dreaming and the blind.

You don’t have eyes within your brain so you couldn’t see light in there if there was any.

@kritiper you do have a light sensitive pineal gland!

Okay, fine, your brain is different than everybody else’s. Your brain has a little refrigerator light in it.
It is seeming as though you didn’t post this question to get an answer. It seems as though you posted the question only so you could challenge all comers.

Count me out.

Couldn’t tell you. I’m a automotive/diesel mechanic, not a doctor. If there was some kind of light show going on in my head at night it would project out my ears and keep me awake at night.

When we see, how is the flow of sight handled. If this requires a separate question, recommend it, and I’ll post that.

A light sensitive pineal gland can’t detect light if there isn’t any. And a pineal gland isn’t an eyeball.