The clocks 'spring' forward this weekend in the UK – two weeks after the switchover in the US – to mark the start of daylight savings time. The change means you'll effectively lose an hour's sleep, but evenings will be lighter and it marks the fact summer is on the way. But why do we have daylight savings time, and why is it out of sync with the US?
Daylight savings time (DST), otherwise known as British summer time (BST), is when the clocks move forward an hour in Spring before moving back an hour for Autumn. In the UK in 2017, DST begins on Sunday 26 March and ends on October 29. Before the clocks go back, the UK is on Greenwich Mean Time (GMT) which then switches to BST for six months.
On Sunday, clocks that would be reading 1am GMT will instead read 2am BST, and sunrise and sunset will be an hour later. While the dates vary each year, Daylight Savings Time typically happens in March and ends in October.
The idea of adjusting the time throughout the year has been around for centuries. During the height of the Roman Empire, an hour could last 44 minutes in winter and 75 in summer.
However, British builder William Willett from Chislehurst lobbied for nationwide adoption of daylight savings time in his 1907 pamphlet The Waste of Daylight. While riding his horse one morning, it is said Willett had a epiphany that "the sun shines upon the land for several hours each day while we are asleep" but there "remains only a brief spell of declining daylight in which to spend the short period of leisure at our disposal."
In other words, Willett's proposal for daylight savings time had one main motivator - for people to enjoy more sunlight. This change was also important for farm workers, for example, who use the extra hour of sunlight to work into the evening during harvest seasons.
Initially, Willett wanted clocks to go forward twenty minutes at 2am on four consecutive Sundays in April, and then to be reversed on four Sundays in September. This was later adjusted to a much simpler idea: a one-hour advancement of clock time in Spring and a one-hour reversal in Autumn.
Willett lobbied for the adoption of DST until his death from influenza in 1915 - just a year before it was adopted as a nationwide policy in the UK in an effort to reduce energy consumption and increase war production during WW1. It was for these same reasons it was adopted in the US in 1918. While this was an emergency law in the UK, it became permanent in 1925 with the passing of the Summer Time Act.
Daylight savings time always starts earlier in the United States – at 2am on March 12 this year – and occurs in the majority of states and territories in the US excluding Arizona, Hawaii and Guam.
Although it was officially adopted in 1918, the idea of daylight savings times in the United States has been linked to Benjamin Franklin, during his time as an American ambassador to France in 1784. In his essay, An Economical Project for Diminishing the Cost of Light, he jokingly suggested the French should rise one hour earlier so as to save candle wax.
While intended as a joke, the theory stuck. If you have an extra hour of sunlight, you're less likely to use artificial lights, thus (in theory) save energy. In 2005, President George W. Bush lengthened daylight saving time by a month, in an effort to reduce US dependency on foreign oil.
This separate adoption of daylight savings time, and the fact the countries are situated in different timezones, plus their differing geography, led to the differences between the US and UK version of daylight savings time.
Although the reason for the change was initially economic, people disagree as to whether it produces any economic benefits. In fact, it's been argued to have notably damaging effects to health and the economy. Not only is the initial change to daylight savings time likely to make you feel more tired, likened to a subset of jet lag, it's also estimated to cost $434 million in the US alone.
A poll in 2011 suggested that 53 per cent of Britons supported moving clocks forward an hour permanently, as opposed to having their sleep schedules interrupted twice a year.
This article was originally published by WIRED UK
