Why do people sleep? A new study points to the brain

The new study suggests that when too much mitochondrial damage is detected in brain cells known as sleep-control neurons, they trigger sleep. These neurons act like circuit-breakers, says Gero Miesenböck at Oxford University, one of the paper’s lead authors, tripping the brain into sleep before too many electrons build up. Sleep simultaneously restores the balance of electrons and allows the mitochondrial damage to be repaired.