You're curled up on the couch, finally relaxing after a long day when suddenly, your heart starts racing. You're obviously ...

Tachycardia is the medical term for a heart rate over 100 beats per minute (BPM). It can be a sign of emotional distress or anxiety, anemia (low levels of iron in the blood), infections, dehydration, ...

Your heart beats about 100,000 times a day. Sometimes it beats faster and sometimes more slowly, depending on what you're doing and whether, for instance, you're all worked up about something. So ...