Asthma is a chronic condition in which the airways of the lungs become narrow due to muscle spasm, inflammation, and excess mucus.

This produces symptoms like trouble breathing, wheezing, and coughing. For some people, these symptoms show up only in response to specific triggers — like pollen or other allergens, exercise, or even weather changes. In others, asthma symptoms flare during sleep or even daily.

There are different categories of asthma, most of which are defined by their triggers or symptoms. For example, nocturnal asthma is a type that comes on at night while you’re in bed; occupational asthma is caused by exposure to specific chemicals or pollutants at work.

RELATED: What Type of Asthma Do I Have?

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