So why do we do it? Because the government tells us to. Congress mandated that beginning in 2007 daylight saving time would start the second Sunday in March and end the first Sunday in November -- an extension of four weeks from the old daylight saving time. States could opt out; only Arizona and Hawaii have. Don't count on saving on energy bills with daylight saving time. Even though DST in the United States came about in the Energy Policy Act of 2005, the leading author on daylight savings time said it only cuts electrical use by 0.5 percent -- if that. A study in Indiana in 2008 showed little change in energy use when parts of the state went to daylight saving time.