Before you go to bed Saturday night, remember to set your clocks back an hour as Daylight Saving Time (DST) ends at 2 a.m. Sunday morning.

The concept of DST emerged in the late 1800s and was first implemented in parts of Europe during World War I. DST came to the United States in 1918 and was made mandatory nationwide during World War II.

The government made DST optional for each state. Arizona and Hawaii do not set their clocks forward or back.

Daylight Saving Time was extended by a month in 2007 by the Energy Policy Act. From 1987 to 2006, the start and end dates were the first Sunday in April and the last Saturday in October.