Have you ever experienced a sudden increase in heart rate while sitting, lying in bed or even during a calm moment at work? The feeling can be unsettling as it often comes without warning or a clear ...

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 ...

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 ...