However, I am constantly reading fiction with people knocked out for hours with no sequelae, so I think most people would be willing to suspend their disbelief for an hour or so.

I am still salty about a fanfic in which a character was clonked over the head and was unconscious from that for half an hour but was confident he didn't have a concussion! (And that wasn't meant to be character confusion; the writer really did think a concussion was something separate from the half hour of unconsciousness caused by the blow to the head ....)