If you're not sure whether you've endured a traumatic event or not, one way to check is to ask yourself if you've had a "slip into coma." This is a common symptom of severe traumatic brain injury (TBI), which is a leading cause of death in young adults. A TBI can occur when the head is hit with a force that causes an injury to the brain. Cognitive function can be severely affected, and people may experience a loss of consciousness or confusion. If you experience any of these symptoms, it's important to get medical help as soon as possible.