Up to 10% of people will suffer a mild head injury (or 'mild traumatic brain injury') in their lifetime and up to 50% of those people will also find they have lingering post-concussion symptoms in the months or years afterwards. These symptoms can include headaches, dizziness, fatigue, irritability, sleep disturbance, reduced day-to-day memory, poor concentration, taking longer to think, 'muzzy' headedness, depression, anxiety, tinnitus, blurred or double vision, sensitivity to light or noise, frustration, nausea, restlessness and sensitivity to alcohol. In such circumstances the 'mild' head...