Sleepy or just bored? The mystery of yawning and why it’s so contagious

Have you ever found yourself starting to yawn just because you saw someone else do it? It’s not your imagination: Yawns really are contagious. In fact, humans can feel the urge to yawn after seeing, hearing or even just thinking about someone else doing it.

Scientists have been trying for a while to figure out why yawns are so easy to “catch”, but for now, they’re not even sure why the yawns you let out when you’re sleepy or bored happen.

It’s possible that a yawn (which is a big inhale and a stretch in your eardrums, followed by a large exhale) serves to cool down your brain or other parts of your body. It could also have something to do with regulating the amount of oxygen in your blood.

It might even be a reflex that serves to keep your body alert when you’re tired or distracted – something that our ancient primate ancestors evolved to keep them from zoning out and ignoring signs of predators.

That’s one theory about why yawns are contagious: If they’re meant to perk us up when we might be in danger, it’s useful for them to spread quickly through a group.

It’s common for social animals such as humans to copy one another’s behaviours to fit in, especially when that behaviour is something that might be useful to their survival. That’s why some research focuses on whether contagious yawning is related to empathy, or our ability to understand and share what other people are feeling.