NASA sleep experts reveal social jet lag, a misalignment between internal body clocks and daily schedules, affects millions.

A test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias), and can sometimes ... In some cases, surgery on the malfunctioning valve can help ease symptoms.

Learn critical heart skipping patterns that signal emergency situations. Recognize dangerous rhythm changes that demand ...

It’s tempting to think that, with our fancy electric lights and indoor bedrooms, humanity has evolved beyond the natural ...