Red-eye flights, all-night study sessions, and extra-inning playoff games all deprive us of sleep and can leave us forgetful the next day. Now scientists have discovered that lost sleep disrupts a specific molecule in the brain's memory circuitry, possibly leading to treatments for tired brains. Neuroscientists studying rodents and humans have found that sleep deprivation interrupts the storage of episodic memories: information about who, what, when, and where. To lay down these memories, neurons in our brains form new connections with other neurons or strengthen old ones. This rewiring process, which occurs over a period of hours, requires a rat's...