Dreamers can definitely stay in the Dream Sphere for long stretches of time, but a permanent detachment from the Waking World isn't strictly possible. Using a Signature Attack or being knocked out during a fight, for example, will send a Dreamer back to reality where they will have some difficulty reconnecting to the Dream Sphere for up to a week. They will also need to at least occasionally pop back to reality to eat and drink in a way that actually refreshes their bodies.

There are instances of Dreamers permanently vanishing from the Waking World, but this is exceeding rare and considered to be the result of a Dreamer being lost in or somehow permanently swallowed by the Dream Sphere.