Under normal circumstances, the human heart rate is in the range of 60-100 times per minute, and in quiet conditions, if the heart rate is around 90 times belongs to normal, but it is a situation that belongs to the upper limit of normal, normal fast. These causes are usually related to the increased sympathetic tone, for example, patients with increased sympathetic tone have the following common factors, usually in mental tension, excessive stress, excessive fatigue, poor rest or sleep, when the heart rate at rest will be relatively too high. In addition, if the patient takes certain medications for a long time, it can also cause the above-mentioned adverse reactions and side effects. If a patient is under prolonged mental stress or has an endocrine system disorder, he or she may have a heart rate of about 90 beats at rest. Such patients need to be monitored regularly, and once the heart rate at rest is 100 beats or more, they must be hospitalized for systematic examination.