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 ...

A recent study observed sleeping participants' pupils during sleep, using a new method that could have implications for studying sleep disorders. Reading time 2 minutes Though sleep is a time to power ...

Birds exhibit unihemispheric sleep, a fascinating compromise between rest and survival. One half of their brain remains alert ...

Dogs’ shenanigans are bound to leave their owners surprised. However, did you know they can even act quirky while sleeping? A recent clip on social media has been capturing this moment in the cutest ...