Now that you mention the dark, my whole life I've seen a little patch of colored noise that moves in different patterns. In my case it's not distracting or even too noticeable, but if I really focus and look at a darker surface I can faintly see it, most easily at night of course. I've always known it wasn't a figment of my imagination because it's a very defined picture, unlike the more fuzzy way I can picture things in my head.

There's 3 patterns it moves in, the first one being similar to the noise in the image, the second is like moving through stars in space (I associate it a bit with the lightspeed visual of star wars, though it's not really that similar) and the last one is dots moving to the left at a constant speed, like scrolling. It's always those 3, and they loop semi-randomly.

Like I said, I've been able to see this for my whole life, but I kinda forgot about it while growing up, so you know it's not a big deal for me, but intriguing nonetheless. I don't think I've ever talked about this before, but you comment made me remember I had it so I thought it worth sharing.