The earliest references to dreams are found in Rig veda which are
mystic than symbolic.
It is said that dreams are manifestations of
evil spirits.
By praying to Lord Varuna, a person can protect himself
from the evil dreams.
Lord Varuna is also called as Lord of Rta, the
Law-giver who distributes the good and evil dreams in tune with the
punya or papa-karma that the subject has to experience.
By praying to
this Lord, the evil dreams are consigned to Trita Aptya. (the 3rd
level of consciousness or antharyamin?).