How long after hitting your head would you notice signs of bleeding in brain? Hit head on corner of concrete wall 7 hrs ago. Have a headache.

variable. This depends on the size and location of the "bleed." something large or in more eloquent areas would probably be noticeable sooner than a small one in not-as-important areas. Very small one might not be noticed at all.In severe cases, you could lose consciousness. Also, if a hemorrhage grows, it could become more noticeable. Somethings can progress over minutes/hours, while others can take days.
Brain injury. If you are feeling dizzy or nauseous you should seek medical attention right away. If there is any weakness in an arm or leg, visual changes or other neurologic changes you need immediate medical attention. However persistent headache could mean concussion and you see a doctor soon. Mild brain injury does have an effect on work and school. Kids are more susceptible than adults.