Nonetheless, unforced insomnia that ends only in death, though very rare, does happen. Consider a disease called fatal familial insomnia (FFI). As described in The Family That Couldn't Sleepby D. T. Max, fatal familial insomnia is a genetic disease, first identified in the 1980s, in which prions—the same kind of mysterious, viruslike rogue protein responsible for mad cow disease and Creutzfeldt-Jakob Disease in humans—caused a rare, always lethal, condition characterized by relentless insomnia. Upon autopsy, the brain seems mostly normal, except that the prions have essentially scoured out the thalamus—a nodule still not well understood, which helps control the body's autonomic nervous system and natural sleep–wake cycles. The affected person experiences increasingly dire symptoms: worsening insomnia, profuse sweating, stiff neck, pinprick-sized pupils, sudden menopause in women, impotence in men, listlessness, tremors, uncontrollable crying, thrashing limbs, elevated blood pressure and pulse, loss of balance, dizziness, and emaciation, ultimately culminating in a state of chronic, agitated, hallucinatory stupor, alternating with ever-shorter periods of lucidity. No narcotic or anesthetic agent has any effect, and the end—generally around 15 months or so after symptoms first appear—is usually awful. Max describes one dying man "howling in the night, his arms and legs wrapped around themselves."
Almost nobody gets fatal familial insomnia, and yet, don't these symptoms strike a terrifying chord in the heart of anyone who's ever spent more than a few nights staring hollow-eyed into the darkness? The exhausted longing for sleep combined with the paradoxical inability to force yourself to "fall" asleep is maddening in that the harder you try, the greater your physiological stress, and the more awake you feel. The sense of existing in a surreal state, all nerves quivering as if expecting at any second that ominous knock on the door by the KGB or the Gestapo (or Homeland Security?), breeds anxiety and dread, an enveloping foreboding that something nearby is wrong and strange and dangerous.
With our poor night vision and relative helplessness before predators that growl and stalk the darkness, we have always felt, from our deepest hominid past, most vulnerable to harm after sunset: the "hour of the wolf" has more than metaphorical meaning. Night and death, sleep and death, have a long history of association. In The Iliad, Hades, the "Kingdom of the Dark," is also the kingdom of death, and it's during the night that the dead visit the living in the form of dreams. To be up and about in this land of the dead seems to be breaking a taboo, to be entering a forbidden borderland between waking and sleeping, living and dying, and risking unpleasant and unsought encounters with ghosts and specters, goblins and ghouls. And encounter them we often do, even if they originate in our own minds, haunting presences from our own lives. As an anonymous Japanese poet once put it, "the night offers toads and black dogs and corpses of the drowned."