Perhaps the word traumatic is to blame for many believing that unconsciousness always results from a TBI. However, this is not the case. You can suffer a traumatic brain injury and not lose consciousness. In fact, it is possible to suffer a TBI and not even know you have one. This refers, of course, to mild TBIs. A concussion, for example, is a form of mild traumatic brain injury and does not always cause a loss of consciousness. However, when dealing with moderate and severe TBIs, it is widely accepted that TBIs in these two classifications always involve a period of unconsciousness. For moderate TBIs, some experts say that unconsciousness occurs for at least 30 minutes but no longer than 24 hours. Others have a much higher threshold for their definitions of moderate brain injuries, with some stating six hours of unconsciousness is necessary. Most agree that short minutes- or seconds-long blackouts don’t qualify as signs of moderate brain injury. With a severe TBI, an injured victim remains unconscious for more than a day.