If you have asthma, you might notice symptoms that pop up only at night or worsen as the evening goes on. Doctors aren't totally sure why this can happen, but which classification of asthma you belong to may dictate how your asthma behaves at night (via Self). There are four types of asthma: mild intermittent, mild persistent, moderate persistent, and severe persistent. Moderate and severe classifications usually mean that you're having symptoms at least one night per week, if not more often.
This could be because there are more triggers present where you sleep, like dust mites or pet dander in your bed. When you spend 7-9 hours in bed, these allergens can interfere with breathing, making sleep difficult. Your levels of the stress hormone cortisol could also increase at night, which causes the airways to become inflamed. If you have other health conditions, they might interact with asthma and make your symptoms worse. Sleep apnea and gastroesophageal reflux disease (GERD) are two conditions that can also make it harder for you to get some shuteye.
Some ways to help treat nighttime asthma are using a rescue inhaler, sipping water, and sleeping in a more upright position (via CNN Health). You could also make changes to your medication dosage or even the timing of taking your medication. Talk to your doctor about your treatment plan and how to best manage nighttime asthma.