Sing or hum a song. Not only does singing improve one’s mood, but humming and singing can actually prove therapeutic! Nasal nitric oxide is known to be broadly antifungal, antiviral, and antibacterial. Concentrations of nitric oxide in healthy sinuses are high and nasal nitric oxide is known to be increased 15- to 20-fold by humming, compared with quietly exhaling.
Ask God’s creatures. Starlings, who are robust singers, exhibit enhanced immunity when compared to their counterparts, non-robust singers. Studies show that singing also increases IgA in the saliva. IgA is a class of antibodies that guard the mucus membranes in the body, including the respiratory mucosa. Of course, you might not want to sing around others if you have an upper respiratory tract infection since it could spread your germs, but otherwise, singing will improve your breathing capacity, reduce stress, and probably lift your spirits!
Kreutz G., et al, Effects of choir singing or listening on secretory immunoglobulin A, cortisol, and emotional state. J Behav Med, 27(6):623-35, 2004.
Weitzberg E., Lundberg J.O., Humming greatly increases nasal nitric oxide. Am J Respir Crit Care Med, 166(2):144-5, Jul 15, 2002.