There are several cases of coughing when lying down, as follows: First, the inflammation of the original respiratory tract inside the lungs is not completely well, and there are remaining remnants that have not been discharged. People sitting and standing during the day are vertical, when sunk in the lungs inside the phlegm, from the bottom to the top is not very good out, but once lying flat into a horizontal position, it is easier to outward discharge. In this process to the large airway or throat, the debris of the discharged phlegm may irritate the peripheral nerves to trigger coughing, which then needs to be helped out with phlegm medicine. Second, bed mites, or dust triggered by allergies, lying down, then the quilt, mattress, pillow are relatively soft, a pressure down airflow upward, may lead to mite debris, cotton fiber crumbs in the space above the body, about half a meter are a lot. At this time, if you happen to be allergic to mites and happen to be in the allergy season, or if your body gets cold in the past two days, it may trigger an irritating cough in the airways. At this time, frequent drying of bedding and mite removal can solve this problem, and there are also anti-allergy treatments for the respiratory tract when it is really serious. Third, due to the environment, as the indoor environment is sometimes dry and you can’t drink water repeatedly at night when you sleep, you breathe more and the outdoor environment is dry, so the moisture in the airway is carried away by the constant airflow, and the dryness of the airway will trigger an irritating cough. The simpler way to deal with this is to increase the humidity indoors, using water steam to help humidify the room.