They come from your memories – of events and skills you have learned, of concepts and ideas that you have created in your mind and that have been stored as memories, and of simple thoughts that you have had that have also been encoded into memories. But dreams also discover previously unrecognized connections between all of these memories, and these new connections represent new information.

Unfortunately, we don’t know the causes of night terrors, in children or in adults.

We dream about the issues and concerns within our lives. For those struggling with mental health issues, it’s not surprising that these concerns take a decidedly negative turn. While dreams can often help us see ways out of these concerns, this would be less likely in those with mental health issues, simply because the concerns are so complex and so resistant to improvement.

There is no evidence of any universal symbols in dreams. Quite the contrary, evidence would suggest that such universal symbols do not exist. But dreams can certainly be interpreted. Chapter 12 in our book, When Brains Dream, specifically addresses this issue. You could also look in Clara Hill’s 2003 book, Woking with Dreams in Therapy: Facilitating Exploration, Insight, and Action, published by the American Psychological Association.

https://www.amazon.com/When-Brains-Dream-Exploring-Science/dp/1324002832

https://www.bookdepository.com/Dream-Work-Therapy-Clara-E-Hill/9781591470281

Melatonin can, indeed, improve sleep in some people and appears to do it with deleterious side effects, so, yes, it promotes healthy sleep. I could find no published studies on its effects on dreams, so it probably doesn’t do much.

The DMN is activated during REM sleep and probably is involved in dream construction. I don’t know of studies of “overactivity” in the DMN, but people who ruminate a lot probably have more DMN activity. But I would say that the rumination is causing the overactive DMN and not the other way around?

We have reported dreams from children as young as 4-5 years old [Self-Representation and Bizarreness in Children′s Dream Reports Collected in the Home Setting Resnick, Jody ; Stickgold, Robert ; Rittenhouse, Cynthia D ; Hobson, J. Allan. Consciousness and cognition, 1994, Vol.3 (1), p.30-45], and David Foulkes has reported them from 3 year-olds [Foulkes, D. 1982. Children’s dreams: Longitudinal studies. New York: Wiley].

This is a vast subject, one that Tony Zadra and I have written a book about, called When Brains Dream. But to try to sum it up most simply, dreaming tells us that there is a vast amount of unexplored information stored in the connections or associations between memories.

https://www.amazon.com/When-Brains-Dream-Exploring-Science/dp/1324002832

It depends on the type of memory. But for typical declarative memories—facts and events—slow wave sleep (stage N3) seems to be most important.