Sputum in the middle of the night is considered to be more likely to be lung infections, especially lung infections caused by tuberculosis, tuberculosis is mainly in the night hot flashes, sweating, coughing up sputum, and even sputum with blood, belonging to the Chinese medicine of yin deficiency caused. Accompanied by phlegm should also be considered whether pharyngitis and bronchial asthma, as well as chronic obstructive pulmonary disease, these three diseases are caused by chronic respiratory tract infections, generally in the quiet rest at night, the vagus nerve is relatively more active, causing bronchial constriction, expectoration is more difficult, resulting in patients coughing up phlegm, always feel that the respiratory tract has a phlegm can not be discharged, the symptoms of self-sense is relatively obvious. Therefore, in addition to the consideration of tuberculosis, sputum in the middle of the night, also does not exclude other chronic lung infections, even including tumor diseases.