The analyst's ‘sleep’ during sessions is a puzzling, troubling, extreme experience, which has rarely been described in the psychoanalytic literature. The author presents a clinical illustration in which her recurring ‘sleep’ during the sessions was approached as an open, central issue. She attempts to explore, understand and integrate this experience theoretically and clinically, first by reviewing and examining the psychoanalytic literature on the subject and on related phenomena, and then, more particularly, by formulating her own explanation of it. She emphasises being in the grip of the psychoanalytic process, and the immersed involvement and converging of patient and analyst, which generate a conjoint state of deep experiential interconnectedness and impact on each other—in particular the impact of the patient's inner world on the analyst. In this context, the author also refers to the notions of ‘the uncanny’, ‘fear of breakdown’ and dissociative self-states and the mitigation of the patient's dissociative self-experience via the analyst's vicarious dissociative experience.