When Is Daylight Saving Time 2018? When You Should Switch Your Clocks

Get ready to lose an hour of sleep. The second weekend in March is here, which means it's time to set the clocks back to mark the beginning of daylight saving time.

The change will happen for residents across the country at 2 a.m. local time Sunday morning, according to the National Institute of Standards and Technology. People all across the country will change their clocks or their clocks will change automatically Sunday morning—with the exception of a few.

Two states in the country, Hawaii and Arizona, will not change their clocks and neither will the territories of Guam, Puerto Rico, American Samoa or the Virgin Islands because those areas do not observe DST, according to NIST.

In areas that do observe daylight saving time, the clock will jump from 2 a.m. to 3 a.m. When DST was introduced part of the Uniform Time Act in 1966, its purpose was to essentially preserve the daylight, according to the United States Department of Transportation. Moving the clocks ahead an hour takes an hour of daylight from the early morning hours and moves it to the end of the day. After the clocks spring forward, the sun will rise later in the morning and set later in the day.

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The second Sunday in March marks the start of daylight saving time in the United States. The clocks move forward one hour at 2 a.m. JEFF PACHOUD/AFP/Getty Images

The reasons listed on the DOT website for DST say that it reduces energy use and crime and prevents traffic injuries. These reasons for keeping DST going have been hotly debated and some people even argue that it has the opposite impact the DOT claims it does.

Florida recently passed a bill in the state House and Senate called the "Sunshine Protection Act" that would keep DST year round. Meaning Florida would set the clocks ahead and leave them there indefinitely. The bill still has to go to the governor's desk and then must be passed in Congress for it to become law. Until then, the clocks will go back in November, on the first Sunday of the month, at 2 a.m.