By setting up a humidifier, you can improve the indoor air quality of your home and improve your breathing. Dry air can dry out your nasal passages all the way down to your lungs, causing you to wake up with a dry mouth and an irritated throat. A cool-mist humidifier may help soothe cough and congestion symptoms., Moisture in the air can thin and loosen mucus, helping you to have more productive coughs and be less congested.