When we change our clocks

Daylight Saving Time begins for most of the United States at 2 a.m. on the first Sunday of April. Time reverts to standard time at 2 a.m. on the last Sunday of October. In the U.S., each time zone switches at a different time.

In the European Union, Summer Time begins and ends at 1 am Universal Time (Greenwich Mean Time). It starts the last Sunday in March, and ends the last Sunday in October. In the EU, all time zones change at the same moment.

> See more information about elsewhere in the world.

Spring forward, Fall back

During DST, clocks are turned forward an hour, effectively moving an hour of daylight from the morning to the evening.

Spelling & grammar

The official spelling is Daylight Saving Time, not Daylight SavingS Time.

Saving is used here as a verbal adjective (a participle). It modifies time and tells us more about its nature; namely, that it is characterized by the activity of saving daylight. It is a saving daylight kind of time. Similar examples would be dog walking time or book reading time. Since saving is a verb describing a single type of activity, the form is singular.

Nevertheless, many people feel the word savings (with an 's') flows more mellifluously off the tongue, and Daylight Savings Time is also in common usage, and can be found in dictionaries.

Part of the confusion is because the phrase Daylight Saving Time is inaccurate, since no daylight is actually saved. Daylight Shifting Time would be better, but it is not as politically desirable. In fact, scientifically misguided politicians sometimes misunderstand. In 1995, the British Time (Extra Daylight) Bill was introduced by John Butterfill, attempting the impossible -- to legislate extra daylight. The bill did not pass.

When in the morning?

In the U.S., clocks change at 2 am local time. In Spring, clocks spring forward from 1:59 am to 3 am; in Fall, clocks fall back from 1:59 am to 1 am. In the EU, clocks change at 1 am Universal Time. In Spring, clocks spring forward from 12:59 am to 2 am; in Fall, clocks fall back from 1:59 am to 1 am.

Nationwide, U.S. restaurants and bars have varied closing policies. In many states, liquor cannot be served after 2 a.m. But at 2 a.m. in the Fall, the time switches back one hour. So, can they serve for that additional hour in October? The official answer is that the bars do not close at 2 a.m. but actually at 1:59 a.m. So, they are already closed when the time changes from Daylight Saving Time into Standard Time. In practice however, many establishments stay open an extra hour in the Fall.

In the U.S., the changeover time was arbitrarily chosen to be 2 am, when most people are at home. This is practical and minimizes disruption. It is late enough to minimally affect bars and restaurants, and prevent the day from switching to yesterday (which would be confusing). It is early enough that the entire continental U.S. has switched by daybreak, and the changeover occurs before most early shift workers and early churchgoers (particularly on Easter).

Some U.S. areas

Daylight Saving Time, for the U.S. and its territories, is NOT observed in Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands, most of the Eastern Time Zone portion of the State of Indiana, and the state of Arizona (not the Navajo Indian Reservation, which does observe). Navajo Nation participates in the Daylight Saving Time policy, due to its large size and location in three states.

A safety reminder

Many fire departments encourage people to change the battery in the smoke detector when they change their clocks, because it can be so easy to forget otherwise. "A working smoke detector more than doubles a person's chances of surviving a home fire," says William McNabb of the Troy Fire Department in Michigan. More than 90 percent of homes in the United States have smoke detectors, but one-third are estimated to have worn-out or missing batteries.

> For information about world calendars, see Calendars through the Ages.