I am sooooooo tired!!!!

I just want to say today that I am freaking exhausted! It boggles my mind that after going through labor and caring for a newborn baby throughout the night for months that we as mothers can get up the next day and put on a happy face, most of the time, and carry on. But the second they start sleeping though the night we (I) take it for granted. They sleep peacefully for months, through the night light little angels. Then one night they decide they are going to wake up at 2 AM and want to play! What the heck?!? I got the baby to sleep again for like an hour and then she was up again. This went on all night long. Then, she was up for the day at 7 AM this mornig, which was early for her anyway. I AM TIRED!! Why? I just don't get it. I didn't just go through labor, I'm not nursing anymore, my body isn't recovering from anything but I feel like I just got hit by a train. I am so confused. Do you think our bodies are hard wired to run off of 3 hours of sleep after we have a baby or what? I want to hear what you have to say on this topic.