Did something different today...
Today, I went in for my scheduled blood donation. At the end of the last one, they had asked me to consider volunteering for a double-red-cell donation. I considered it, for about five seconds, and decided that I'd volunteer at the next opportunity.
The donation went quite well, for a change. They hooked me up to a different machine than the one they use for a standard donation, since this procedure's different. Basically, it starts out about like a regular blood donation, but after the blood is extracted, the plasma is separated from the red cells, and put back into the donor---and then the process starts again, until the cycle's been gone through twice. Hence, the phrase "double-red-cell donation."
It took longer than a standard donation, unsurprisingly. As I lay there, I felt myself getting chilly, and after a minute or so, I figured out why. When the plasma had been out of my body, it had lost some of its body heat, and putting it back in chilled me somewhat. The nurse was quite surprised that I'd figured that out, but confirmed that I was correct.
Aye, well...now I'll not be eligible to donate again until September.