Yawning!?!?!

Question: I heard Yawning was when you were tierd but then i heard it was a lack of oxygen to the brain.
Which one is true?

---

---

Answers: I heard Yawning was when you were tierd but then i heard it was a lack of oxygen to the brain.
Which one is true?

---

---

They kind of go together. When you are tired you breathe less deeply/constantly so your body makes you yawn to get more oxygen into the brain. More oxygen means more respriation, meaning more energy if made!
There are other theories too, but this is he most realistic.

---

---

Both. When you are tired, your breathing slows.

---

---

---

---