Swollen and painful gums after sleeping may be caused by diseases such as apical periodontitis, pulpitis, gingivitis and external stimulation. 1. Periapical periodontitis: it is a purulent infection of the alveolar bone around the root of the tooth, which may lead to symptoms such as swollen gums and toothache, and the symptoms of swollen and painful gums may be aggravated after sleeping. 2. Pulpitis: Most of the time, the pulp is exposed due to the stimulation of dental caries and secondary infection, which can also cause gum swelling and pain after sleeping. 3. Gingivitis: Mostly caused by plaque stimulation, gum infection, can also lead to after sleeping gum swelling and pain. 4. External stimulation: For example, trauma, taking too hard food, picking teeth and other processes to stab the gums, can also cause after sleeping gums swollen and painful. There may be other reasons for swollen and painful gums after sleeping, it is recommended to go to the hospital in time for examination and treatment as prescribed by the doctor.