system
Given the following post, respond as if you're commenting on Reddit:
human
When you're sick why do symptoms seem to get worse at night?

Right now I've got a cold and during the day I feel somewhat okay and my nose is fairly clear, but right now as I'm getting ready for bed I'm feeling really achy and my nose is all stuffed up.  Why do the symptoms get worse at night?
gpt
Your symptoms probably get worse because of circadian rhythm effects. Your immune system is more active at night - you get higher concentrations of inflammatory cytokines and the like - leading to more pronounced symptoms as your immune system combats infection "with more fervor". In the specific example of inflammatory cytokines, the greater degree of inflammation promoted by their elevated levels is likely the thing leading to your feeling achy.