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 ...

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 ...

Light sleep is the beginning of your sleep cycle and your body's way of winding down. Breathing, heart rate and muscle changes prepare your body for the deeper sleep to come. Light sleep is broken ...