"Spring Forward, Fall Back" was proposed by Ben Franklin as a way to save energy. Proponents later argued that it reduces traffic accidents and crime, promotes shopping, provides more time to play golf all supported with varying degrees of science, wishful thinking and fantasy.
Daylight saving was first adopted in World War I, abandoned after the war and then restarted by the US during World War II. It lasted three years before it was repealed again. Reintroduced in the '60s, daylight saving time has been modified ever since and is followed by many countries around the world with different places having different start and stop dates. To add to the confusion, Hawaii, part of Arizona, and the territories including Puerto Rico and the Virgin Islands do not observe daylight saving time.
Many of us find the resetting of the clocks annoying but naturally wonder if there's any science behind daylight saving time conserving energy.
In 1975 the Department of Transportation reported that daylight saving resulted in cost savings but that report was soon dismissed by the National Bureau of Standards. Simulations whether it be by California Energy Commission (2001), the Department of Energy (2006) or the many other researchers that have built computer models are less meaningful than actual usage measurements. Luckily a few studies have used real world data, not simulations.
A study involving Australia around the time of the 2000 Olympics showed there was an increase, not decrease in electrical usage based on comparisons of neighboring states where two had started daylight saving time and one hadn't.
In the US, a household level study based on data from Indiana (where some counties had daylight saving in 2004 and all had in 2006) between 2004-6 showed that daylight saving time resulted in more electricity being used as decreased illumination costs were more than offset by higher heating and cooling costs. This research addressed only a small part of the energy consumption pie: in 2004 residential usage was 21% of total energy consumption less than industrial (33%) and transportation (28%) and commercial (17%) but research should be done on the other energy users.
Michael Downing, author of Spring Forward: The Annual Madness of Daylight Saving Time stated that daylight saving has never realized energy savings but it succeeds at getting Americans to spend more money.
My conclusion is that daylight saving time is not going away in my lifetime. Politicians don't care about the shaky scientific case for energy savings but do care about campaign funding and re-elections.
Daylight saving is a minor topic. The much more important point is that in general we should be extra cautious of any program or policy whose justification changes over time as the data shows each previous explanation to be questionable or false.