system
Given the following post, respond as if you're commenting on Reddit:
human
When we are sick why do we feel worse at night?
gpt
Cortisol is a steroid hormone that curbs white blood cell activity. More cortisol is in your blood during the day, so your white blood cells are less active in fighting infections.

At night, there is less cortisol in your blood, your white blood cells will detect and fight infections more readily, and you will experience more of symptoms of infection (i.e. fevers, sweating).