Hey, just want to jump in here, does anyone know off hand which systems of neurotransmitters experience shifts in levels of expression during dreams/sleeping/unconsciousness etc.? Is there a global depression of all types of neurotransmitters while sleeping, or are specific types predominantly affected?

I'll google it as well, but can anyone recommend any books/papers about the subject?

edit: oops, nm, just found this in the tutorial section. But the last question still stands.