Dry cough at 3:00 or 4:00 a.m. may be lung cancer, or it may be caused by dry environment, cough variant asthma, and other diseases such as laryngitis. 1. Lung cancer: Lung cancer is considered to be caused by smoking, occupational exposure, air pollution and other factors, and the patient will have irritating dry cough, hemoptysis, shortness of breath and other symptoms, so the patient will have the symptom of coughing at 3:00 or 4:00 in the morning. 2. Environmental dryness: When patients have a dry cough at night, they may be in a drier environment, leading to dryness of the respiratory tract, so they will have a dry cough at three or four o’clock in the morning. 3. Cough variant asthma: the cause of cough variant asthma is not yet clear, considered to be related to genetic, environmental and other factors, the patient’s main symptom for the stimulation of dry cough, especially at night is more obvious, but also chest tightness, tightness of breath and other symptoms. Therefore, the patient has the phenomenon of dry cough at 3:00 am and 4:00 am. 4. Other: laryngitis, tuberculosis, bronchitis and other diseases can also lead to patients with 3:00 am 4:00 am dry cough symptoms. The symptoms of dry cough at 3:00am and 4:00am may be caused by lung cancer, environmental factors or other diseases. It is recommended that the patient should consult a doctor in time to find out the cause of the disease.