What a Heat Wave Does to Your Body | The New Yorker

Later that day, the researchers drained the tub and analyzed the soup. They told me that my performance in the chamber counted as a passing grade. My temperature hadn’t entered the danger zone, in part because I’d sweated out nearly a litre of water each hour. On the other hand, my sweat had contained a lot of sodium—possibly a sign that my body hadn’t adjusted to high-temperature conditions. I may not have been ready for the heat.