(National Geographic) With an extra hour of sleep and an earlier sunset, daylight saving time (also called daylight savings time) ends this weekend.

That means clock confusion is once again ticking away, giving rise to hotly debated questions: Why do we spring forward and fall back? Does daylight saving time (DST) really save energy? Is it bad for your health? Here are some answers from the experts.

When Will Daylight Saving Time End in 2013?

For most Americans daylight saving time will end with a “fall back” to standard time on Sunday, November 3, at 2 a.m. Most states “sprang forward” an hour to begin DST on Sunday, March 10.

But the federal government doesn’t require U.S. states or territories to observe daylight saving time, which is why residents of Arizona (except for residents of the Navajo Indian Reservation), Hawaii, Puerto Rico, the Virgin Islands, American Samoa, Guam, and the Northern Marianas Islands won’t need to change their clocks this weekend.

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