A yawn is an involuntary reflex that involves opening the mouth wide and taking in a deep breath, followed by a slow exhale. Several theories exist about why we yawn, but researchers have not proven ...

It took scientists six months to train Alexandra the red-footed tortoise, but by midsummer 2009 she’d finally learned to fake a yawn. A formal experiment came right after. Once per day for several ...

Yawning is an automatic body response to tiredness or stress. Less commonly, excessive yawning can also be a sign of an underlying health condition. It can be related to the vagus nerve, sleep ...