Daylight saving time (DST) is the biannual event when we forget whether to put our clocks one hour back or one hour forward, and whether this means we’ll get some extra sleep or not.
The clocks went forward on Sunday night, which means that in the UK we’re back on Greenwich Mean Time (GMT) and sunrise and sunset will be about one hour earlier than the day before – so there will be more light in the morning.
In the UK the clocks go forward 1 hour at 1am on the last Sunday in March, and back 1 hour at 2am on the last Sunday in October.
The period when the clocks are 1 hour ahead is called British Summer Time (BST). There's more daylight in the evenings and less in the mornings (sometimes called Daylight Saving Time).
When the clocks go back, the UK is on Greenwich Mean Time (GMT).
Why do we do it?
In 1905, British builder William Willett raised the idea of introducing DST. Liberal Party MP Robert Pearce introduced a bill to the House of Commons in February 1908. The first daylight saving bill was drafted in 1909, presented to parliament several times and examined by a select committee. However, it was opposed by many, especially farmers, and the bill didn't make it into law.
During the first world war, Germany became the first country to implement DST, on 30 April 1916, in order to save fuel for the war effort. Thereafter, other countries followed suit and the concept was adopted by Britain. DST was first used in the UK on 21 May 1916.
The best place to check, if you're ever unsure is the direct.gov website. They detail the time and date of each clock change so that you won't miss it!
Nowadays, smart phones and computers do this for us automatically, meaning it is systematised.
Does every country do it?
Daylight Saving Time is not observed in Hawaii or Arizona (with the exception of the Navajo Nation), and it’s also skipped in Puerto Rico and the Virgin Islands. When it comes to the rest of the world, it’s a mix. In fact, only about 70 percent of countries follow Daylight Savings Time.
What are time zones and why do we have them?
Time zones are based around solar time – the idea that that no matter where on the planet you are, noon is the middle of the day when the sun is highest, while midnight is the middle of the night.
The expansion of the railway, and other transport and communications, as well as trade globalisation, during the 19th century created a need for a more unified time-keeping system, and time zones were introduced. There are countries that are a couple of hours ahead of us, and some that are full days ahead of us!
What if we had one time zone for the entire world?
If the whole planet lived by a single time, noon would be the middle of the day in some places, but it would be morning, afternoon, evening and night, in others.
Henry & Hanke argue that we should adopt Greenwich Mean Time as a universal time; a single time zone for the whole world. The same time everywhere regardless of the position of the sun in the sky. This wouldn't mean that you would go to bed during the day and wake up at night. It would simply mean that your day to day patterns would change. 11am would be day time for some countries and evening for others.
There has been proposals and research into abolishing the time zone completely and having a universal one. Some countries have already moved toward fewer time zones. Since 1949, China has had only a single time zone even though geographically the country spans five. In 2010, Russia abolished two of its time zones, dropping the number from 11 to nine.
Let us know what you think on Twitter by using the hashtag #timezonetweets
A TED talks video below, discusses the subject.