4. Observed worldwide: More than 70 countries observe a daylight saving time shift. It's also called "summer time" in some countries.
5. Not in Arizona and Hawaii: "Standard time" is observed yearlong in Arizona and Hawaii, the only U.S. states that do not shift to DST.
6. You can survive: The Better Sleep Council suggests you start making changes in the days leading up to the time change to help your body adjust. Changes include going to bed 15 minutes earlier in the days before, exercise, avoiding caffeine and 20-minute naps following the change.
7. Worth it? Depends on whom you ask? The U.S. Department of Transportation says yes because a study shows it cuts electricity usage by 1 percent. Other studies dispute this finding. The ski industry opposed a proposal to extend DST in Colorado, saying it cut time resorts had to prepare for opening.
8. Grades may fall: Some sleep-deprived students have tested a grade lower than during well-rested times. Sleep specialist Lisa Meltzer, PhD, suggests putting kids to bed 15 minutes earlier in the four nights before the time change.
9. It pays and costs: Retailers see a boost in sales during DST. Other industries cite extra costs from longer hours to prepare for the time switch.
10. When does it end? DST ends 2 a.m. Sunday, Nov. 1.