Octopus sleep includes a frenzied, colorful, ‘active’ stage

Octopuses cycle through two stages of slumber, a new study reports.

First comes quiet sleep, and then a shift to a twitchy, active sleep in which vibrant colors flash across the animals’ skin. These details, gleaned from four snoozing cephalopods in a lab in Brazil, may provide clues to a big scientific mystery: Why do animals sleep?

Sleep is so important that every animal seems to have a version of it, says Philippe Mourrain, a neurobiologist at Stanford University who recently described the