On next Saturday night people in Europe will put their clocks forward by one hour, to be more precise, at 2 am at night they will set it to 3 am. The so called Daylight Saving Time (DST) will start, which will end on the last weekend of October, where the clocks will be put back to standard time. But why do we do this, and even more importantly, is it useful?
In 1784 in the USA Benjamin Franklin first brought up the idea of a change of local time during the summer months to reduce the consumption of candles. This, however, was not meant as an honest recommendation, but more as a joke. More seriously proposed was the seasonal changing of time in the United Kingdom by William Willett in 1907. He made the point that lots of sunny hours are wasted during the summer months, since most people spend them sleeping (later on complaining about the missed early hours), whereas a similar amount of daylight is missed in the evening when one comes home from work. Thus, he suggested to introduce a seasonal summer time, which should originally be achieved by putting the clocks forward by 20 minutes on 2 am for four consecutive weeks in April. His idea was not accepted until 1916 after the German Reich introduced DST.
But still it is not clear, if this changing of time has any benefit. There are many pro and contra arguments. Such as in the recommendation from Willett, people will spend more of their waking hours during sunlight. The other main goal of DST was the saving of energy, since there would be less artificial light necessary because the usual activities would take place on hours where there was still daylight. Anyhow, several studies showed that this is not the case. Worst case calculations even suggested that DST increases the energy consumption. This is due to increased need for heating in the early hours (when it is darker and colder as it would be in standard time) and bigger requirement of air conditioning for example in the later hours (when it is still warmer than in standard time).
There are controversial discussions about the subject, but for the nearer future, no change of the current system can be expected.
 http://www.webexhibits.org/daylightsaving/franklin3.html (last access: 23.03.2013)
 http://www.webexhibits.org/daylightsaving/willett.html (last access: 23.03.2013)
 http://webarchiv.bundestag.de/cgi/show.php?fileToLoad=1890&id=1015 (last access 23.03.2013)