Reverie Syndrome, also known as Daydream Syndrome, is an incurable illness from Zero Escape: Zero Time Dilemma that results in the patient experiencing life in a dream-like state of mind, hence its name. Maria, the sister of Carlos, is afflicted with this illness.
Those affected by Reverie Syndrome enter a state where they experience loss of memory, and consistently drift in and out of consciousness, in what can be seen as being in a continuous daydream. Despite the obvious symptoms, no abnormalities occur in brain function, and the cause of the illness was unknown.
Truth of the syndrome
As revealed by Akane Kurashiki in the Power Room, the illness is actually caused by a person with the innate gift of being an esper subconsciously accessing the morphogenetic field, or possibly between stuck in constant SHIFT mode, trapped in alternate histories. Due to the overload of information, the brain effectively puts itself on stand-by.
It is heavily implied the reason for the recent increase in cases of Reverie Syndrome around 2028 was due to innate espers subconsciously pulling information about the the upcoming destruction of humanity from the morphogenetic field. This includes the Radical-6 pandemic, Antimatter Plant Explosions and the religious fanatic's plan to destroy humanity.