We can witness the spirit world in our dreams. Often times we are out of our bodies and in the spirit world while dreaming. We can witness the dead and some of the powers of that world. Sometimes, a person can witness the spirits of deceased friends and family members. And the spirits of living people as well.
An angel of the Lord came to Joseph in a dream to tell him that the child was of the Holy Spirit and not to be afraid to take Mary as his wife.
Mathew 1:20. But while he thought about these things, behold, an angel of the Lord appeared to him in a dream, saying, “Joseph, son of David, do not be afraid to take to you Mary your wife, for that which is conceived in her is of the Holy Spirit.
Spirits are in the spirit world and not in our heads. Saint Joseph was in the spirit world with the angel while dreaming.
Nightmares have demonic influence. The devil tempts the recovering alcoholic by putting a can of beer in his or her hand in a dream. What we are dealing with is a complex hidden battle between us and demonic forces on a subconscious and unconscious level in our dreams. They prey on our weaknesses.
"Saint Augustine of Hippo (d. 430 C.E.) left several writings clearly expressing his opinion that dreams can come from several sources: from the divine, from below, or simply from everyday life."
"St. Augustine also discusses lucid dreaming in one of his letters – as evidence of life after death."