That's hyperphantasia. My brain too take me on weird adventures before sleep, but for me it can happen without any control over it like some sort of flashback. It doesn't last long, like a 2-3 seconds . When kid i always had this sort of hallucination that would happen randomly where i open a door very slowly and in the other side is some sort of library and in the center a huge hourglass spinning. All happening in slow motion.

The author has snippets of her book here. But, they're a bunch of funny stories throughout her life and how she's been dealing with depression. I've read it multiple times and I love the book.

Here's a quote from the website:

What kind of stories are in it?

Of the new stories, there are two new stories about my dogs, a story about a letter I wrote to my future self when I was ten, a story about the use of fear and shame as motivational tools, a story about the time my mother tried to take my sister and I on an adventure and ended up getting us all lost in the woods, a story about all the illogical internal rules I have for how reality should be and what happens when reality doesn't give a shit about my rules, a story about a toy parrot, a story about a lie I told as a child that spiraled completely out of control, a story about my identity and how I use it to prevent myself from realizing how shitty I actually am, and a cautionary tale about what happens when you try to fix everything about yourself all at once.

Guided mindfulness meditation I guess? I don't have a specific link.