The normal range of the heart rate is 60-100 beats per minute, which is measured when the patient is at rest. The heart rate is affected by many factors, such as fever, cold, emotional stress, and strenuous exercise, which may cause the heart rate to increase, while the heart rate slows down during deep sleep. Some diseases can also trigger a faster heart rate, such as anemia, hyperthyroidism, and heart failure, which are relatively common diseases that can trigger a faster heartbeat. There are also some diseases that may trigger a slower heart rate, such as hypothyroidism and acute right ventricular myocardial infarction, which can cause bradycardia in relative terms.