Altered states of consciousness are something that all humans experience, scholars suggest that all humans have an innate draw to entering altered states of consciousness as they allow you to access
information
stored
elsewhere
in your brain. 

Sleeping and dreaming are considered altered state of consciousness.  Musicians and artists enter altered states sometimes when they work, they might get into a kind of flow where they are accessing different parts of their brain that allow them to produce extraordinary artwork. 

Shamanic practitioners are practiced at voluntarily entering these states to be able to access information that lives in, what Jung called, the collective unconscious.  They can then use that information to carry out healing that can be done to support themselves and others.

Even Einstein spoke openly about accessing his genius in the in-between state of sleep and waking.