Increased vagal tone does not only occur at night. Changes in vagal tone are manifested as either an increase or a decrease in the excitability of the vagus nerve. The vagus nerves are the 10th pair of cranial nerves and are mixed nerves containing sensory, motor and parasympathetic fibers. At night, when people are in a sleep state, sympathetic excitability decreases and parasympathetic innervation prevails, i.e., increased vagal excitability occurs. Increased vagal excitability can still occur during the day, for example, bathing in a stuffy bath, chronic hypoxia, and after a full meal can lead to elevated vagal tone, and some patients may experience nausea, vomiting, tingling of the lips and mouth, or even fainting. Vagal tone varies with different states of the organism, and increased vagal tone does not just occur at night. When the patient has the corresponding symptoms, it is recommended to consult a doctor in time.