I believe it's the higher power trying to communicate with us.

A way for our subconscious to grapple with the unbearable weight of being, I reckon.

Things weighing on your mind in waking life taking the shape of demons and saints.

Sometimes they are real like premonition and sometimes just a dream that related to your life.

Your subconscious working on things you deal with in your conscious mind and life..be attuned to answers that you're looking for in dreams..sometimes it happens that way.

Stress, and possibly core wishes.
Though my sister and I have had dreams that came true. The universe is creepy like that.

I was listening to an episode of Lore last night to fall asleep that talked about how dreams have a history of being interpreted as messages from the divine.

And how there used to be a clairvoyant physician that would go into a dream-like trance in order to receive instructions about treatment. She cured herself of her own illness by reciting instructions that she received from a disembodied voice about how to prepare some specific type of medicine to her brother.