All kids get a fever from time to time. A fever itself usually causes no harm and can actually be a good thing — it's often a sign that the body is fighting an infection.
But when your child wakes in the middle of the night flushed, hot, and sweaty, it's easy to be unsure of what to do next. Should you get out the thermometer? Call the doctor?
Fever happens when the body's internal "thermostat" raises the body temperature above its normal level. This thermostat is found in a part of the brain called the hypothalamus. The hypothalamus knows what temperature your body should be (usually around 98.6°F/37°C) and will send messages to your body to keep it that way.
Most people's body temperatures change a little bit during the course of the day: It's usually a little lower in the morning and a little higher in the evening and can vary as kids run around, play, and exercise.
Sometimes, though, the hypothalamus will "reset" the body to a higher temperature in response to an infection, illness, or some other cause. Why? Researchers believe that turning up the heat is a way for the body to fight the germs that cause infections, making it a less comfortable place for them.
