The Guardian of Dreams: The Neglected Relationship Between Sleep and Psychoanalysis.

Knowledge about sleep was very limited at the time when Freud published his seminal work on the interpretation of dreams. He was also not interested in sleep, which was considered a problem of physiology; however, sleep appears to have a central role in his model, since dreaming is considered the guardian of sleep. The function of dreaming, according to Freud, is to protect sleep from disruption, with the dream working to avoid repressed stimuli interrupting the "biological" function of sleep. Before neurophysiological studies provided evidence that sleep is not a passive state, Freud also recognized sleep as an active process, as human beings voluntarily withdraw their attention from the external world to actively move to sleep. The discovery of REM sleep in the 1950s led psychoanalysts to see sleep as the necessary background to the occurrence of dreaming. Although Freud dismissed the clinical importance of sleep disturbances, viewing them as the somatic expression of an instinctual disturbance which would disappear during psychoanalytic treatment, successive authors highlighted the fact that sleep disturbances might have a more specific psychological significance. The similarities between the loss of self that occurs during sleep and the fragmentation of the identity experienced during schizophrenia represent an interesting and yet not fully explored area of research. Thanks to Freud's work, the desire to sleep assumes the important role of a psychological, active factor that contributes to the occurrence and function of sleep.