The heart is the body's hardest-working muscle. Whether you're awake or asleep, or exercising or resting, your heart is always at work. It pumps blood through arteries to deliver oxygen to organs and ...

Many people find themselves lying in bed, suddenly aware of their heart beating faster than usual. When the room grows still, the pulse in your chest can feel louder, stronger and impossible to ignore ...

A heart that beats too fast can leave you lightheaded, dizzy, out of breath or feeling fatigued.

Sitting quietly at your desk, watching TV, or lying in bed at night, your heart should be taking it easy – beating steadily and calmly at somewhere between 60 and 80 beats per minute for most healthy ...