(Re 23°C: things like humidity, fans, etc would vary it, but it was interesting observing my sleeping patterns and correlating it to temperature, at that time. Hey, I was stuck in the wrong country for two months, I needed something to do. I'm not about to redo the "experiment" if I can help it. Also, here we probably have the aircons set a bit lower than I said above. We don't have a thermometer or hygrometer, so I have to go by reported temperatures, but I have no reason to think they fib.)
I have a nice little chart which shows the apparent temperature, given the humidity and environmental temperature. Fascinating reading. For example, the other day when it was 40°C and 50% humidity, for most people that gives an apparent temperature of about 55°C, or 63° if you're in full sun (that's 145°F, if you needed the conversion).
Yum.