How animals sleep can reveal a surprising amount about their health, mood, and personality. Dogs, in particular, show a wide range of sleep behaviors — from deep REM cycles to quick, light naps — and ...

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 ...

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 ...

Most animals close their eyes when they sleep. But did you know some amazing creatures can actually sleep with their eyes ...