Global Geological And Climatic Events

Explained: Daylight Saving Time (DST)


From UPSC perspective, the following things are important :

Prelims level : DST

Mains level : DST and its significance


  • Clocks in Europe went back an hour on Sunday, signalling the end of Daylight Saving Time (DST) this year. The same will happen with clocks in the United States next week.
  • In the Southern Hemisphere, the opposite has happened.
  • Thus, clocks have gone ahead by an hour — in New Zealand and in Australia.

Daylight Saving Time (DST)

  • DST is the practice of setting the clocks forward one hour from standard time during the summer months, and back again in the fall, in order to make better use of natural daylight.
  • It is in use during the period from spring to autumn (or fall), when Europe and the United States get an extra hour of daylight in the evening.

When did the system of putting clocks forward and back start?

  • The idea of fixing clocks to save energy and to make the day seem longer than it is, is over 200 years old, but its sustained implementation took longer.
  • Written accounts suggest that a group of Canadians in Port Arthur (Ontario) were the first to adopt the practice on July 1, 1908, setting their clocks an hour ahead. Other parts of Canada followed suit.
  • In April 1916, during World War I, with Europe facing severe coal shortages, Germany and Austria-Hungary introduced DST to minimize the use of artificial lighting.
  • Many other countries on both the warring sides followed suit. The US introduced it in May 1916, and has stuck with it ever since.

Why use DST?

  • No daylight is of course, actually ‘saved’ — rather, the idea is to make better use of daylight.
  • So when it is autumn (or fall) in the Northern Hemisphere, and days are typically beginning to become shorter and nights longer, clocks are moved back an hour.
  • The rationale behind setting clocks ahead of standard time during springtime was to ensure that clocks showed a later sunrise and a later sunset — in effect, a longer evening daytime.
  • Individuals were expected to wake up an hour earlier than usual, and complete their daily work routines an hour earlier.
  • The governments decide to in effect transfer an hour of daylight from evening to morning, when it is assumed to be of greater use to most people.

Who uses DST?

  • Countries around the equator (in Africa, South America, and southeast Asia) do not usually follow DST; there isn’t much variation in the daylight they receive round the year in any case.
  • India does not have a DST, even though there are large parts of the country where winter days are shorter.
  • Most Gulf countries do not use DST — during the holy month of Ramzan, this could mean delaying the breaking of the fast for longer.
  • Morocco has DST, but suspends it during Ramzan. However, Iran has DST, and stays with it even during Ramzan.
  • Countries in East Asia and Africa mostly do not have a system of DST.

DST across the world

  • Dates for this switch, which happens twice a year (in the spring and autumn) are decided beforehand.
  • By law, the 28 member states of the EU switch together — moving forward on the last Sunday of March and falling back on the last Sunday in October.
  • In the US, clocks go back on the first Sunday of November.
  • Russia experimented with having permanent DST in 2011, but that created a situation in which it was dark at midday at some places.
  • So in 2014, it returned to switching from DST to standard time in the autumn.

What is the change with respect to Indian time?

  • Now that DST has ended in Europe and clocks have gone back an hour, the time difference between London and India is five and a half hours (and that between Paris or Berlin and India is four and a half hours).
  • Britain is now on Greenwich Mean Time (GMT); until Saturday when it was on DST or British Summer Time (BST).
  • Earlier the time difference between London and India was four and a half hours (three and a half hours for Paris or Berlin).
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