Definitely. People should be seen by a doctor when they lose consciousness from a blow to the head, because of the risk of concussion (as well as other kinds of brain injury). Concussion can last for days or longer, and failing to rest puts the victim at greater risk of complications or re-injury.

http://www.cdc.gov/concussion/pdf/Facts_about_Concussion_TBI...

I wish I had a better source than that, because I found the advice on p. 4 kind of ambiguous (whether "should be taken seriously" is meant to make an emergency room visit more urgent or less urgent).