What is the dream realm called?

The Plane of Dreamers is the plane where we visit while sleeping. It consists of schools of different classes.

While out of our physical bodies, an advanced soul takes the form of his semi-astral appearance and goes to school, learning things, which will help him in his physical existence—

Heavy atmosphere on this planet! This appearance of fog is due to the surrounding thoughts of the physical.

This is the plane of the dreamers. 

Their material and spiritual thoughts are congested and somewhat confused. In his sleep, the advanced mortal may rise to more spiritual realms of thought where greater lessons are learned.