Home air quality

Not sure if this is the best place for this, so if theres a better sub to ask, please let me know.

Air quality in my home seems to go to shit overnight and im not entirely sure whats causing it. Every morning when i wake up my air purifier is reading high and we can feel it. Its back to normal after 2 or so hours. I do live in a high humidity area, so im sure that contributes, but I didnt know if there were factors I should be concerned about. Any tips would be appreciated. We do have carbon monoxide censors throughout the house.