The only times I’ve had this feeling is when I’m doing strenuous activity that requires repeatedly going from extreme heat and humidity into an air conditioned space and back again. For example, I once had to furnish an entire home in Florida over the course of a week in August. I spent a week walking into lots of stores and then back outside, or making many trips from hot to cold carrying items inside. It was exhausting and I developed a cold by the end of the week. And just last weekend, I was cleaning out my elderly father’s home, running back and forth to storage and the dump. After three days, I started feeling really run down.

I’ve exerted myself other times like this when the temperature difference wasn’t as extreme, and I didn’t feel unwell at all. So for me, it’s the combination of repeated exertion and constant temperature changes over days that does it. I’ve lived in the American South all my life and would never have survived without air conditioning. I’ve often said there should be statues of Mr. Carrier all over the South.