Because your body is low on blood. It takes up to 2 hours to make that pint that you donated back. And when you are low on blood your body tends to pass out, although it dosen't happen to everyone. I am the one who always passes out just at the end of giving blood.

~sara~

when doctor was trying to establish a connection to administer morphine and a sedative, my veins kept collapsing. Why did this happen?