Our knowledge of concussions has increased and our treatment has changed substantially in recent years based on new research. Some of the major changes include the awareness that "minor head injuries," frequently called "bell-ringers or dings," are in fact concussions; many relatively minor head injuries take longer to heal than previously believed; concussions can occur without loss of consciousness, vomiting or other symptoms. Often times, headache, dizziness, "fogginess," poor attention span and unusual behavior are the signs of concussion. Another major change is the knowledge that thinking, "exercising the brain" and nearly all cognitive tasks have the same effect on prolonging concussion symptoms and slowing recovery as does physical exertion. Consequently, the management of even these minor head injuries has changed dramatically. Restricting mental exertion and physical exertion until asymptomatic and then gradually increasing each is the cornerstone of this treatment strategy.