When will the clocks change tonight and why do we use daylight saving time?
DAYLIGHT saving ends in October and begins in March each year.
Here's the date when the clocks go back in 2018 and why we make the change.
When do the clocks change for Greenwich Mean Time?
The clocks go back again on Sunday, October 28, 2018, which marks the end of daylight saving time and the return to Greenwich Mean Time (GMT).
GMT is the mean solar time at the Royal Observatory in Greenwich, London.
The change heralds the approach of winter by ensuring there’s more daylight in the mornings and less in the evenings.
For example 6pm in BST will then become 5pm GMT, meaning it is darker earlier in the evening.
However 8am BST will become 7am GMT, making the mornings lighter.
To avoid confusion, many use the phrase "spring forward, fall back" to remember when the clocks change.
The clocks went forward at 1am on Sunday, March 25, 2018, which resulted in lighter evenings across the UK.
Do I gain or lose an hour when the clocks change?
As the clocks go back, at 2am on October 28 to be precise, you will gain an hour - either for more partying or extra sleep.
Your smartphone and other internet-connected devices like tablets and computers will often change the time automatically instead of requiring you do it manually.
Why do we have BST and DST?
Whether Daylight Saving Time is effective is the topic of much debate.
Despite trying other methods of clock-changing, such as double summer time (GMT + 2 hours) and a permanent British Summer Time (GMT + 1 hour), the current method has remained in place since 1972.
Supporters say it reduces traffic accidents in winter, saves energy, boosts tourism and encourages more people to exercise outdoors.
The golf industry says one extra month of Daylight Saving Time can generate up to £246.6million a year in extra sales and fees.
Critics say keeping BST all year round would mean darker mornings, which are dangerous for children walking to school.
They say the energy-saving argument is invalid if people use fans and air-conditioning in the warmer months.
A YouGov poll in 2011 found 53 per cent of Brits support moving clocks forward permanently, while 32 per cent oppose the change.
When permanent BST was trialled in northern Scotland from 1968 to 1971, a record number of people were killed or seriously injured.
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What is Daylight Saving Time?
Daylight Saving Time (DST) was created by William Willett in 1907 in a bid to stop people wasting valuable hours of light in the summer months.
By setting the clocks back in winter, Brits get an earlier sunrise and earlier sunset.
In summer the sun rises and sets one hour later than it would without DST.
In a pamphlet called "The Waste of Daylight" Willett suggested clocks should be advanced by 80 minutes over four stages in April, and reversed the same way in September.
Willett died of the flu in 1915 and Germany adopted his clock-changing plan on April 30 the following year.
Britain followed suit one month later on May 21, as World War One was underway.
The Summer Time Act of 1916 was passed by Parliament and the first day of British summer was reported as May 21, 1916.
