The animal kingdom is full of fascinating adaptations, and one of the most intriguing is the ability to sleep with one eye open. While humans drift into deep slumber with both eyes closed, several ...

This story was originally published by CalMatters. Sign up for their newsletters. If you’re serving hard time inside a California prison, you’ll often find yourself stuck in a cramped cell with a ...

Birds resting on a beach or a wire often look calm, almost detached from what is happening around them. But that stillness can be misleading. For many species, sleep is not a full shutdown. One eye ...

Humans do very little when we sleep. This might not seem like a big deal, until you look to the dolphins as they sleep and swim with the pod. Or fur seals, who can sleep while watching out for sharks.

Have you heard the saying about “sleeping with one eye open”? It’s a bit of metaphoric advice about staying vigilant—and a way to describe very light restless sleep. But sleeping with eyes open is ...

If you're serving hard time inside a California prison, you'll often find yourself stuck in a cramped cell with a complete stranger. You hang a bedsheet to manufacture the semblance of privacy between ...