system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do cold/flu symptoms get worse at night?

Fevers spike, cough and congestion gets worse, body pain intensifies. Is it about the circadian rhythm?
gpt
Your immune system's inflammatory response is heightened at night. Sleep is when the body and brain do work to repair themselves. This means your symptoms worsen and your temperature raises to fever in an attempt to kill the virus or whatever bug you have. Even allergy symptoms like to get pretty bad at night with congestion. This is often why the PM version of medication has ingredients to help you sleep through it all.