An Enertron is a special device in 2300 A.D. that allows Humans to obtain a full night's rest in moments. It allows the survivors of the Day of Lavos to remain healthy, though the agony of hunger and an empty stomach is not cured by the machine. This fact led to a famous line and sound effect that read, "But you're still hungry..."
Theory and Analysis
Enertrons probably had to have some effects on the brain, as they let people get a full night's sleep in seconds. Perhaps the technology used was a precursor to that developed for the Records of FATE.
Thanks to Thought