Why do people feel sick after sleeping in AC rooms?

Pulmonologist Dr Manas Mengar said ACs can reduce indoor humidity, which dries out the nose, throat, and airways. He said dirty AC filters may circulate dust mites, mould and allergens, triggering sneezing, coughing and asthma flare-ups. Sudden shifts between extreme outdoor heat and freezing indoor temperatures can irritate the respiratory system, especially in sensitive individuals, he added.