I recommend checking out https://www.brain.fm/
Invented to have the brain of a neuroscientist and the heart of a musician. Our AI (or extended human intelligence) creates all the music in brain.fm.
If you dig around you can find a lifetime subscription for about $40.
The idea is it stimulates the brain to increase focus, creativity, and relaxation, depending on the waves targeted.
That's really amazing. Thank you!
Also, check out
Ultimate Brain
by Tom Kenyon, but I don't see much point of it anymore since Brain.fm.