Darn Early

Just got back from Madam's little cataract surgery with no problems. I would just like to know why surgery is scheduled at such early hours. We had to be there at 645a and since it is all the way inside the Perimeter off of I-75 we had to leave the house at 545a. I will note that there is not much traffic at that time of day. All's well that ends well but there might be an afternoon nap in the offing.