Lying still will reduce the heart rate, but not all people’s heart rate will fall. Calmly lying down to rest, the sympathetic nervous excitability will decline, the body’s adrenaline level will have a certain degree of reduction, the heart rate level will also be relatively reduced, manifested as a slow heart rate, belong to the physiological changes. However, some people do not necessarily experience a decrease in heart rate when lying down, such as patients with hyperthyroidism, the patient’s body has a high level of thyroid hormones, the heart rate level is also higher when lying down, patients with anemia will have symptoms of hypoxia, but also in the rest of the heart rate of the symptoms of fast. In normal people, the heart rate will decrease to a certain extent when lying down, but if the heart rate is still fast, it is important to look for the cause.