The heart never sleeps. The muscle constantly pumps life-giving blood through the veins. And yet, when mind and body get a good night’s rest, the organ that never rests can also take it easy. Depending on age and physical fitness, the heart rate drops to as little as 45 to 55 beats per minute. For comparison: During the day, the resting heart rate of healthy adults is between 60 and 80. Stress, sport and other activities quickly drive it to 140 and more. It is no coincidence that heart attacks occur more frequently after waking up in the morning – when the pump has to work harder again.