Asthma patients have a more than 3-fold greater risk of developing narcolepsy than those without asthma. Narcolepsy is a chronic sleep disorder characterized by overwhelming daytime drowsiness. A Nationwide Case-Control Study in Taiwan, conducted by a group of researchers from Department of Psychiatry, Tri-Service General Hospital, Institute of Brain Science, National Yang Ming Chiao Tung University, among others, to examine the association between asthma and narcolepsy and determine the effects of therapeutic corticosteroid or bronchodilator use, also found that the use of inhaled corticosteroids could decrease such risk. 

The nested case-control study used data derived from Taiwan’s National Health Insurance Research Database between 2000 and 2013. Out of 2008 subjects identified from the NHIRD (502 patients with narcolepsy and 1506 controls), almost all with narcolepsy had almost three times the level of previous asthma diagnosis than controls. Compared to those without asthma, patients with asthma had an adjusted odds ratio (OR) of 3.181 for narcolepsy comorbidity (95% confidence interval [CI]: 2.048– 4.941, p< 0.001). 

However, the use of inhaled corticosteroids was found associated with an approximate 53 percent reduction in risk of narcolepsy comorbidity in patients with asthma.