Heart rate, or heart pulse, is the speed of the heartbeat measured by the number of contractions of the heart per unit of time — typically beats per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excrete carbon dioxide. Activities that can provoke change include physical exercise, sleep, anxiety, stress, illness, ingesting, and drugs.The normal resting adult human heart rate ranges from 60–100 bpm.