system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How come when you have a sore throat it gets significantly worse if you sleep with the fan on?
gpt
Your throat relies on staying moist. But the moving air from the fan tends to remove moisture from you, so your throat dries out more. That makes it feel even worse than it did. 

The effect doesn't happen much if you point the fan at your legs instead of your head.