We often think of yawning as something that happens when we're tired but the answer is much more mysterious. Nij and the kids meet Dr Kathleen Maddison at the Centre for Sleep Science for an adventure that starts all the way back in caveman times! 

For more great kids podcasts, download the free ABC listen app (Australia). There you’ll find more kids news podcasts, educational children’s stories and storytelling, podcasts from your favourite characters like Bluey and Hey Duggee and plenty more of the best kids podcasts like Imagine This, Dino Dome and News Time. For all ages from 0–4-year-olds, 5–8-year-olds, 8–10-year-olds, tweens and teens. And you can watch our kids shows on ABC iview and on the ABC Kids and ABC Big Kids channels of YouTube kids.