Changing the clocks disrupts sleep patterns. This correlates with decreased economic efficiency. Researchers estimated in 2000 that the daylight saving effect implies a one day loss of $31 billion on the NYSE, AMEX, and NASDAQ alone.[17] Sleep disruption also correlates with a significant increase in fatal accidents the Monday after a Sunday shift, with the larger increase in autumn.[18]

http://en.wikipedia.org/wiki/Daylight_saving_time

Some of the accidents also have to do with the sun being in people's eyes during rush hour where it hadn't been before,etc. so slows people down/they have to adjust (half awake :-) etc. I remember that happening; you go for a month and work your way through the sun being in your eyes a bit at a time so you can get use to it and very "suddenly" it's at a different place. It made me angry :-) because I had just gotten so it was high enough so I could see/read the stoplight and then it was low again so I couldn't see the light changing (so was likely to go through a yellow/red one). If you are travelling on a road going "east" on the way to work in the morning, it can be a big problem.

They were saying there's usually not really as much energy saving as is quoted because people run air conditioning more because they're up later, etc.

Don't forget the people late for Church :-) often happens Easter or Palm Sunday for the old change date.