I've heard this a lot from plenty of people, including my wife and mother. The problem is that I have just heard of it verbally. I did a bit of research and did not find anything conclusive.
If someone hits their head, do not let that person sleep for the next 1/2 hour. If that happens that might lead to brain damage or even death.
I am skeptical about this. My son (1.5 years) has fallen plenty of times and hit his head. My wife says don't let him sleep. The way I see it is that if someone hits their head hard enough to cause damage, they will tend to fall asleep.
So I am guessing that this is a confusion of cause and effect. Thinking that sleeping after the hit is what causes the brain damage, rather than sleep is caused by the brain damage. I keep telling my wife to ask the pediatrician, but she ignores me, because she is stubborn.
What does the skeptics think of this.