I have similar nightsweat problems, so I did something close to this once: https://www.wikihow.com/Clean-a-Bed-with-Baking-Soda
If you Google "clean mattress with baking soda" you'll find a bunch of similar recipes. Lots suggest using essential oils, which I didn't use.
The results were decent when I did it. Definitely de-funkified the mattress a bit, and removed some of the stains. It was hardly like new, but it was definitely better than before.
I semi-regularly dream that I'm playing a video game, but it usually is a more like a hybrid between controlling a video game character, and being the actual character.
It usually manifests itself as some alternate reality version of WoW (because I've played that more than any other game, I assume). Sometimes I even think to myself, "it's amazing that I've never seen this part of WoW before!"