Inclusion Criteria:  Patients aged 16 years and older (no upper age limit) Presenting to the ED with a concussion Concussion defined as a traumatically induced alteration of mental status (either defined as loss of consciousness and/or amnesia) Patient is Glasgow Coma Scale score of 13-15 on initial presentation to the ED Patient needs to be able to start using HeadOn within 14 days of their head injury  Exclusion Criteria:  Patients aged under 16 years old Patients requiring surgical management of their cranial injury Significant other associated injuries requiring hospitalisation (spinal injury, fractures, abdominal, cardiothoracic or vascular injuries) Does not have capacity to give consent Non-English speakers Patient in police custody or in prison