One more thing to worry about…don’t yawn too hard. Hayley Black nearly died in the UK after yawning so hard she broke her neck. She had just woken up to make her baby daughter a bottle when she saw the baby yawn and yawned herself. She instantly felt an electric shock through her body and her arm got stuck in the air. At the hospital, doctors found that two bones in her neck had shot forward into her spine from the force of the yawn.
She had emergency surgery and doctors said it was 50-50 whether she would survive or walk again. Black spent six months in a wheelchair and had to learn to walk again. She now has permanent nerve damage and fibromyalgia, which causes chronic pain. She still can't yawn without feeling panicked, which is completely understandable. Add “yawning” to the ever-growing list of things you’re supposed to be scared of.
Source: Oddity Central