IF your passing out was NOT related to a more serious medical condition and you don't hit your head when you fall to the floor, then yes, in time, when your body stabilizes, you will regain consciousness. When people faint, it's caused by not enough oxygen getting to the brain--usually from hyperventilation (more carbon dioxide than oxygen), but while you are lying down, your breathing returns to normal, your oxygen levels return to normal, and you wake up again on your own.
However, if fainting occurs REGULARLY, you should see your physician as this could indicate a heart problem, Virtigo, hypoglycemia, or similar conditions.
at 9:32 AM on Jun. 18, 2010