The United States has six different time zones. The time zones are Hawaii, Alaska, Pacific, Mountain, Central and Eastern. Hawaii time is two hours ahead of Alaska time; all other time zones are one hour apart. During Daylight Saving Time, the names of each of the U.S. time zones change. For example, Pacific Standard Time becomes Pacific Daylight Time. The Department of Transportation is responsible for making sure that Daylight Saving Time is observed.
India is ahead in time of all six of the U.S. time zones. In some instances, it can technically be “tomorrow” in India. For example, it can be evening in the U.S. while it's the following day and date in India.
India is 15.5 hours ahead of Hawaii time; 13.5 hours ahead of Alaska time; 12.5 hours ahead of Pacific time; 11.5 hours ahead of Mountain time; 10.5 hours ahead of Central time; and 9.5 hours ahead of Eastern time.
Daylight Saving Time
During Daylight Saving Time in the U.S., clocks are turned ahead one hour. Daylight Savings Time starts on the second Sunday of the month of March at 2 a.m. and ends on the first Sunday in November at 2 a.m. Originally, Daylight Saving Time began in April and went through October, but an extension was established in 2007. There are a few areas of the United States that don’t observe Daylight Saving Time; they are Hawaii, Arizona, Puerto Rico, American Samoa and the U.S. Virgin Islands.
Jet lag is the effect of traveling on an airplane from one time zone to another. Since we can cross time zones in just a matter of hours, our bodies don’t have enough time to adjust to the difference. This isn’t an issue when traveling by train or boat. Aside from being on a new sleep schedule, those with jet lag may also find that they have trouble making decisions. Your internal clocks needs time to reset itself, and this can take about one day per hour. This means that if you’re crossing into a time zone that’s 11 hours different from what you’re used to, it could take almost your entire trip to adjust, which could make for a difficult vacation or business trip.