Every animal with a brain needs sleep. A few creatures without one do, too; even jellyfish enter a sleep-like state.

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 ...

Double eyelid surgery is one of the most common aesthetic procedures in East Asia, but experts note that improper techniques can result in severe complications, including functional damage to the eyes ...