Why do you yawn in your sleep

As your brain transition to different times of day or activities, it may induce a yawn. It’s like your body’s internal signal telling you something’s up. For example, you do yawn when it’s time for bed as your body prepares for sleep. And, you tend to also do it when you’re bored because your body is going from concentration and alertness to distraction and lower energy.

On a side note, that’s why you should get up and take breaks or walk around every 90 minutes or so when you’re working on something. If you catch yourself yawning, that’s your internal clock telling you to get up and move around.

Before bed

At night, we become less alert, and that can encourage a yawn. Even though there’s a lot of mystery surrounding this bodily function, we do know that certain chemicals in our brain can induce a yawn. One of these chemicals, adrenocorticotropic hormone (ACTH) spikes at night, and that’s one potential reason that we do it right before bed.

When bored

While a yawn doesn’t necessarily mean you’re bored, it doesn’t rule it out, either. We know that when our brain isn’t properly stimulated, its temperature drops and that can encourage yawning.

Tired

The act of yawning increases your heart rate, so one theory is that if you’re tired, this short activity can give you a quick burst of energy. If you find yourself doing it at inopportune times during the day, your body may be trying to wake you up.