Sleep is a natural state of bodily rest and an indispensable part during the lifetime. Sleep is important for restoration, energy preservation, brain development and memory processing. Sleep can be understood differently in psychoanalysis. It depends on how the psychoanalyst explores the psychodynamics of sleep. The significances of sleep from a psychoanalytic perspective are as follows: 1) the acquisition of affection and interest from motherhood in the period of pre-oedipal stage; 2) the reflection of desire to relieve the stress by throwing external difficulties into the unconscious and changing it to the reemergence of Oedipus complex; 3) the process that eros leads a life against the force of thanatos. Dreams help sleep achieve its own purposes by playing the role of a field of conflict resolution and functioning as a source of energy for eros. The comprehension of sleep from a psychoanalytic viewpoint breaks new ground because it promotes the psychiatrist to feel empathy for people who complain of sleep disturbances.