Tonight, we have to move our clocks one hour forward, as daylight savings time arrives three weeks early this year. The WaPo has a nice history on the history of DST.
The clock shift was originally designed to create more leisure time. William Willett, the British architect and golfer who came up with the idea in 1907, wanted to stuff more light into the day so people could play games after work. But it took a war for his proposal to become reality: Germany adopted daylight time during World War I to save fuel; the U.S. and Britain quickly matched the enemy's move.
Ever since, changes in time laws have been driven primarily by war and energy crises. FDR called daylight time "war time." (Woodrow Wilson caved to farmers and reverted to what the farmers called "God's time.") During the 1970s energy crisis, and again in 1986, the prospect of fuel savings won expansions of daylight time. This time, Markey, a Massachusetts Democrat, teamed up with Republican Fred Upton of Michigan to get daylight time started yet another few weeks earlier, again with the expectation that the move would save oil.
Of course, if we were really serious about conserving energy, dozens of other moves would do so far more efficiently, but if that's the excuse politicians need to improve life in a single stroke, so be it. In Britain, Parliament is considering a move to adopt daylight time in the winter and double daylight time in summer. In Washington, that would mean a 9:40 p.m. sunset in late June. Ahhhhh.
The practical argument for daylights savings time is that it saves energy, cuts crime, and decreases auto accidents. Most people are asleep during sunrise (including criminals), but almost everyone is awake at sunset. Pushing the dark off later in the evening pays practical dividends.
But it's also nice having longer days to hang out, play sports, spend outdoor time with the family. There are few things more depressing than winter evenings, when it's dark at 4:30 in the afternoon. Add an hour of daylight, or even two, and things are suddenly much nicer in the evenings.
So who's against it? Farmers used to be, but with GPS and other modern technologies increasing their efficiencies, not so much anymore. Airlines apparently don't like it because it complicates gate times in international flights, though that seems kind of a lame excuse. That leaves parents with kids waiting at bus stops (or walking/biking to school) in the morning. They obviously prefer the kids get to school in daylight than in the dark.