If I hit my head how long do I have to wait to go to sleep?

The time is up to you, but get someone to waken you after a few hours and check how you feel. A concussion can occur which may take days, weeks or even months to subside. Do something like a field sobriety test when you awaken, touch fingers to nose, know your location, time of day and the date. avoid bending over. the blood flow can make you faint.