It's possible to train your mind to do this. It's not just musicians who find their inspiration in dreams.

Albert Einstein and Salvador Dali practiced naps while holding an object over a plate. When they dozed off and dropped the object, the clang would wake them and they could better remember their thoughts from the dream-like state moments before.

https://www.fastcompany.com/3023078/how-dali-einstein-and-ar...