Daylight saving time is the practice of setting clocks forward an hour from March until November to gain more daylight during the summer. According to the Library of Congress, it was first enacted in 1918 as a fuel cost-saving measure during World War I. It became federal law in 1966.

For the past four months, we’ve been on standard time. But overnight Saturday, we’ll turn our clocks ahead one hour at 2 a.m., effectively making it 3 a.m. (So don’t schedule any important meetings at 2:30 a.m., because that time won’t exist Sunday — and is not a great time for a meeting, anyway).

Daylight saving time starts Sunday, despite sleep experts (and the president) hoping to eliminate time changes.