The Nightmare King revealed to Lyra that the Sleepless Nocturne was not a curse, but a desperate attempt by the city's subconscious to prevent a catastrophic event. A being known as "The Devourer" threatened to consume Somnium, erasing its very existence. The city's collective unconscious had created the Sleepless Nocturne to keep The Devourer at bay, but at a terrible cost: the gradual draining of Somnium's life force.