An AP story about the recent vote to extend Daylight Savings says:

July 28,2005 | WASHINGTON -- Daylight-saving time would start three weeks earlier and run through Halloween under a change included in an energy bill approved Thursday by the House. The energy legislation was expected to be passed by the Senate, probably Friday, and sent to President Bush. The time change is supposed save energy because people have more daylight in the evening and do not have to turn on lights. The House had approved a two-month extension -- one in the spring and the other in the fall. But that was scaled back after airline officials complained that the extension would cause problems with intentional flight schedules. Farmers said the change would adversely affect livestock.

Can somebody explain to me how a sheep knows what time it is?