Sounds similar to experiences inside sensory deprivation chambers.
In the SF Bay Area, there’s a company called reboot floatation spa , where you can book time floating in body temperature epsom salts inside a box that blocks noise and light.
I also experienced intense visual imagery and extraordinary ability to concentrate on thoughts while my other senses were deprived. And then I got sleepy
I tried an Epsom salt deprivation chamber and while it was nice I did not experience any visual imagery or anything that wowing. I felt very relaxed and I became sleepy as well. I think it was for about an hour, maybe I should have booked a longer session?
I have also done a sensory deprivation chamber/float tank, but I mostly experienced nausea, from the miniscule amount of water movement. Otherwise it felt like a really bad night of insomnia - lying in bed and feeling trapped.
In the SF Bay Area, there’s a company called reboot floatation spa , where you can book time floating in body temperature epsom salts inside a box that blocks noise and light.
I also experienced intense visual imagery and extraordinary ability to concentrate on thoughts while my other senses were deprived. And then I got sleepy