The causes of coughing after falling asleep at night should be analyzed and judged according to the specific situation, which may include postnasal drip syndrome, cardiac insufficiency, or acute attack of chronic bronchitis, as follows: 1. Postnasal drip syndrome: If there are symptoms such as nasal congestion and runny nose, if you cough when you fall asleep at night, you should consider the presence of postnasal drip syndrome, and you can improve rhinoscopy to clarify the diagnosis, and at the same time give antihistamine and other drugs for treatment. 2. Cardiac insufficiency: If you are an elderly person with hypertension or coronary artery disease and cough at night, you should consider the presence of cardiac insufficiency and improve your cardiac ultrasound and myocardial enzyme profile in time for clarification, and give diuretic and vasodilator treatment. 3. Acute attack of chronic bronchitis: If you are an elderly person with a long-term history of smoking, you should consider the presence of postnasal drip syndrome. If you have a long history of smoking, you should consider the possibility of an acute attack of chronic bronchitis, which can be treated with cough, phlegm and asthma medication.