Why do we yawn and Why is yawning contagious?

Wakes Us Up

As mentioned earlier, sleepiness is associated with higher temperatures and boredom. Because yawning brings down our core body temperature and intensifies our arousal level, yawning is one way to wake ourselves up when we’re tired. It’s also why we yawn so much in the early morning to shake off the last of sleep inertia, and in the moments before bed as a last bid for consciousness before we turn in.