Concussion, also known as minor head trauma, is the most common type of traumatic brain injury. It is typically defined as a head injury with a temporary loss of brain function. Symptoms include a variety of physical, cognitive, and emotional symptoms, which may not be recognized if subtle. A variety of signs accompany concussion including headache, feeling in a fog, and emotional changeability. Physical signs (such as loss of consciousness or amnesia), behavioral changes (such as irritability), cognitive impairment (such as slowed reaction times), or sleep disturbances. Fewer than 10% of sports-related concussions among children are associated with loss of consciousness.