msnbc.com
updated 6:31 p.m. ET, Wed., Oct . 29, 2008
If you've been falling behind on sleep, this is the weekend to fall back into bed for an extra hour — and take advantage of the transition from daylight saving time to standard time.
The time change is part of a longstanding tradition, in which most Americans push their clocks ahead an hour in the spring ("spring forward") and turn them back an hour in autumn ("fall back"). The change officially takes place at 2 a.m. daylight saving time on Sunday, Nov. 2 (which instantly becomes 1 a.m. standard time).
Last year, lawmakers shifted the schedule slightly, setting the changeover for the first weekend in November rather than the last weekend in October. The goal was to extend the energy savings that are thought to result from daylight saving time.
The idea behind daylight saving time — or summer time, as it's known in other parts of the world — is to use the extended daylight hours during the warmest part of the year to best advantage. Timekeepers shift some of that extra sun time from the early morning (when timekeepers need their shut-eye) to the evening (when they play softball).
The shift reduces the need for lighting during the evening, and that's why daylight saving time is considered an energy-saver — that is, as long as there is morning sunlight to spare. Now that the days are shorter, the daylight-saving advantage has largely dissipated.
With the clocks turned back, it will be lighter (or at least less dark) in the morning, but darkness will fall earlier in the evening.
Not everybody goes along with the daylight-saving plan. Arizona and Hawaii, for example, stay on standard time all year round. Each state or country comes up with its own schedule for the switch, and that schedule may be subject to change.
Around the world, Canada and the members of the European Union operate similar summer-time shifts. And yes, some countries in the Southern Hemisphere move their clocks forward an hour at this time of year, in time for the coming summer there.
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If you're in a fall-back time zone, you'll want to savor that extra hour of shut-eye: A major study released this year by the National Center for Health Statistics indicated that sleep deprivation was linked to all sorts of health problems, including smoking and obesity.
