Sleep, dreaming, and mental health: a review of historical and neurobiological perspectives.

Theories as to the function of sleep and dreaming and their relationship to emotions have been studied since the beginning of recorded history. Earliest historical records show the predominant view to be that dreams were considered divine in origin and only later did dream theory become linked with the functioning of the brain, perhaps most famously in psychoanalytic theory. The development of sleep laboratory techniques ushered in a new era of the dream study and their relationship to mental health. In this review we outline the history of theories about the genesis and function of dreams and sleep and their relationship to mental illness from ancient mythic and religious views to the first tentative scientific approaches to the ascendency of psychoanalysis and ultimately to the modern era of neuroscience.