Old Wive's Tales  

if it's just a normal knock to the head you can let them sleep,but i think if they have concusion(vomiting or dizziness)then don't let them sleep,just incase they have a skull facture or a bleed,think that's right

Actually I know that this is true, I don't think that you have to wait for 6 hours but if a child ( or anyone for that matter) hits their head, especially close to the temple area, it can cause a concusion (sorry about the spelling) and if the person goes to sleep it is possible to slip into unconsience. I would look it up online or ask a doctor because I am sure that they would be able to give you more information about it. But no it is not a wives tale and does deserve some looking into. Hope that helps and happy mylotting.

If its just a little bump on the head its fine to let them sleep but if one of my boys fall and get a bump on there head I usually make sure that they dont sleep for the next hour or 2 in case of concusion. Usually signs of concusion is dilated eyes,vomiting and very tired. Then its time to go to the docs.