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 ...

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 ...

Since the January 3 capture of autocrat Nicolas Maduro in a US military raid that killed dozens, Caracas resident "J" has been unable to sleep -- one of countless Venezuelans left psychologically ...

Some animals do it for survival, while others have evolved this ability for different reasons. It might seem strange, but these animals have developed abilities to rest while staying alert to their ...