If you have asthma, you are more likely to experience this condition due to so many reasons. Asthma gets worse in the night because your chances of getting exposed to its triggers are very high in the night. Asthma triggers are allergens, emotional stress, smoke, cold hair, etc. There are different kinds of microorganisms that are basically asthma triggers; they live tightly around your bed. That's why when you sleep in the night, and they gain entry into your airways, they might cause the inflammation of the airways, and this will also cause the airways to become narrow.
Having pets around in your room can also flare up this condition in the night. Most of these pets release their dander, and when they spend so much time in your room, these particles will be everywhere in your room, especially on your bed. Animal dander can also trigger asthma. The air tends to become cold during the night, that's why your asthma could get worse in the night, especially when you get exposed to too much of it.