A concussion is a mild traumatic brain injury—or mTBI—caused by a blow or jolt to the head or body that causes the brain to shake, according to the Children's Hospital of Philadelphia. Since it doesn't take a visible head-on collision to get a concussion, it's important to know the signs of injury.

Symptoms include headache, nausea, dizziness, balance and vision issues, sensitivity to light or sound, sleep troubles, difficulty thinking, and even emotional issues. Crying for no reason can be a sign as well. Symptoms including a seizure, weakness in the limbs, slurred speech and confusion necessitate a n emergency call.