Insomnia occupies a peculiar threshold position within the depth-psychology corpus: it is simultaneously a symptom, a messenger, and a site of psychological confrontation. The literature treats it along at least three distinct axes. First, the mythopoeic register, represented most forcefully by James Hillman, reads sleeplessness as an encounter with the Nycian brood — the offspring of Night whose visitations demand discriminating attention rather than pharmaceutical suppression. Second, the neurobiological-addictions register, pursued by Brower and Sugden, identifies insomnia as a universal withdrawal symptom crossing all DSM-IV substance categories and a robust predictor of relapse, linking it to dopaminergic dysregulation and hippocampal plasticity. Third, the grief-and-loss register, developed by O’Connor, situates insomnia as a dysregulatory consequence of bereavement, where classical biological sleep pressure is redistributed or depleted in ways that pathologize the marital bed as a grief cue. Jung’s own corpus registers the term only indexically, placing insomnia adjacent to inspiration and instinct — a marginal but suggestive co-location. Janet’s hysterical patient, terrorized by the thought of permanent sleeplessness, dramatizes an early clinical encounter with sleep-anxiety that anticipates contemporary CBT-i formulations. Across these registers the tension is consistent: is insomnia resistance to unconscious process, or is it itself an unconscious communication demanding response?