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 ...

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 ...

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 ...