Central Time is 2 hours ahead of Pacific Time. The mainland U.S. has four time zones (Alaska and Hawaii each have their own time zâ¦ones, which makes a total of 6 different time zones for the U.S.). From west to east, the mainland U.S.'s time zones are: Pacific Time, Mountain Time, Central Time and Eastern Time.
It includes a sensor strapped to the wrist which can measure the pressure in the aorta, the main artery close to the heart, where high blood pressure does most damage. A sensor in the watch records the pulse wave of the artery, which is then fed into a computer together with a traditional blood pressure reading from a cuff. In most people the pressure in the aorta is 10mm Hg lower than in the arm, but in some, especially younger people, it is as much as 30mm Hg lower.
How Apple Watch measures your heart rate. The heart rate sensor in Apple Watch uses what is known as photoplethysmography. This technology, while difficult to pronounce, is based on a very simple fact: Blood is red because it reflects red light and absorbs green light.