Some birds sleep in the air. Swifts, for example, hunt down bugs high in the sky 24 hours a day from the time they leave their nest until they return six months later. Some landbirds make transoceanic ...

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

A few weeks ago when I was out cycling with some friends, we saw a few birds who looked like they were sleeping. Someone asked me what they were doing, and I said they were resting or sleeping but I'd ...

Animals have evolved to sleep in extreme ways — for example, taking micro naps during parenting, sleeping on the wing during migrations and dozing while diving.