Apocalyptic Despair Syndrome or Asymptomatic Demise Syndrome (henceforth as ADS) is a form of mass hysteria that took hold of most Safe Zones that created shortly after The Great Panic began to subside. Separate from the mass waves of suicide also occurring, ADS was the name given to the phenomenon of extremely depressed or distressed survivors suddenly dying in their sleep with no pathological or physiological cause of death to be found. It was generally described as people literally succumbing to the feeling that tomorrow wasn't worth living for, when it still looked likely that the Safe Zones would collapse and a complete zombie victory seemed inevitable; after a prolonged period of such stress and depression their minds and bodies just gave out.