The International Date Line roughly aligns with the 180 longitudinal line. Traveling east, an hour is gained for each zone that's crossed. Traveling west, an hour is lost for each zone that's crossed. The United States has six time zones, their numbers are two through seven. From east to west, the names of the U.S. time zones are Eastern, Central, Mountain, Pacific, Alaskan, and Hawaiian.
Olympic athletes travel from all over the world to compete.
They must often cross multiple time zones. Some of these athletes will begin conditioning themselves to a new time zone before a trip. They'll do this by setting their clocks for the time of the country in which they'll be competing. Human Olympians aren't the only ones that travel. Animal Olympians, like the leatherback sea turtle, migrate long distances.