The England Rugby website has some good videos about concussion, i.e. causes, symptoms, red flags, recovery and returning to play after concussion.

I agree with everyone who said that being knocked out for an hour would be considered a serious medical emergency, and following a car accident would mean a trip in an ambulance or maybe even an air ambulance. It's possible they'd already be in the ICU or at least being seen by doctors (scans, etc, to check for brain bleeds and similar) by the time they come around. If there's a brain bleed (which is what doctors will be worried about and scanning for if someone's been unconscious for that long) then they'd have emergency surgery. After anything like that, the patient would be kept in hospital and not let home the same day. I don't know how long they'd have to stay in hospital for, but even without being unconscious for an entire hour, lots of head injury patients would be kept in overnight for observations. Patients with mild concussion are sent home the same day. Mild concussion often doesn't involve being knocked out at all, or it involves being knocked out only for a few moments.