Curious Kids: if our bodies are happy at 37℃, why do we feel so unhappy when it’s too hot outside?

You’re right. Most people’s bodies are happiest when their inside temperature sits around a nice 36.5-37.5℃. These temperatures allow your body to work the best. But your body temperature does go through small changes. It can be a bit lower when you’re asleep. It can also change during the day when you feel hungry, tired or cold. And when you’re sick, your temperature can rise. That’s when you might have a fever.