Toothache in bed at night is, in most cases, a sign of pulpitis. The typical manifestation of pulpitis is the aggravation of pain at night, the cause of which is not particularly certain. It is generally believed that the cause is related to the postural factors. During the daytime, people are usually in an upright or sitting position, when the head and face are high in relation to the heart, and the head and face receive relatively less blood at this time, so the pain is not particularly obvious. However, at night, when the person is lying down while sleeping, the heart and head are on a horizontal line, so the head and face will receive more blood, and its swelling will be more obvious, thus causing more severe pain. There is another reason, which we generally believe is psychological. For most patients, during the day, due to the pressure of study and work, which distracts people’s attention, they are not particularly sensitive to pain, and at night, before going to bed, there is not much going on, so they will naturally feel the pain getting heavier and heavier, and it is more and more unbearable. This is why at night there are many patients who go to the dentistry department and hang an emergency room to check their toothache.