There are many reasons why teeth hurt at night and not during the day, the common ones are pulpitis, apical periodontitis, dental caries and so on. 1. Pulpitis: is an inflammatory lesion that occurs in the pulp of the tooth, at night due to the change in position leads to increased pressure in the pulp cavity, there can be tooth pain at night and no pain during the day. 2. Periapical inflammation: It is an inflammatory disease that occurs in the tissues around the root tip of the tooth. It can be manifested as occlusal pain, swollen gums in the apical part of the root, etc. It can also appear as pain at night and no pain during the day. 3. Dental caries: also known as tooth decay, early generally no self-awareness of symptoms, only manifested as white or brown spots on the teeth. Later, as the disease develops, cavities may appear, and you may experience toothache at night or when you eat stimulating foods (e.g., sour, sweet, etc.). There may be other reasons why your teeth hurt at night but not during the day, so it is recommended that you go to the hospital in time to find out the cause and standardize the treatment under the guidance of a professional doctor.