When do the clocks change and why do we have daylight saving?

The clocks 'spring forward' on Sunday morning as British Summer Time (BST), also called Daylight Saving, begins.

Why do we change the clocks twice a year - and what does the clocks changing mean for your lie-in?

What is BST?

The period when the clocks are one hour ahead is called British Summer Time (BST), also known as Daylight Saving Time, or DST.

During BST there’s more daylight in the evenings and less in the mornings.

When do the clocks change? The clocks will go forward by an hour at 1am on Sunday, March 27. So does that mean the clocks go forward or back? We lose an hour in bed on Sunday as the clocks go forward. Some people like to use the mnemonic 'spring forward, fall back' to remember that clocks go forward an hour in spring and back in autumn (fall).

Why do we change the clocks? The main purpose of winding the clocks on an hour from GMT is to make use of the daylight, giving us longer evenings (although for a short time, if you're an early riser, you will notice darker mornings). Supporters of DST also say it saves energy consumption by reducing the need for lighting and heating into the evenings, although this is disputed. The Royal Society for the Prevention of Accidents (ROSPA) says the number of vulnerable people killed in road accidents spikes after the clocks go back in autumn. The most recent research estimates that adopting British Summer Time would have the net effect of saving around 80 lives and 212 serious injuries a year, although this estimate is now quite old.

Where did the idea of changing the clocks come from? There had been various proposals since the 18th century about shifting time to maximise daylight hours, but it was builder William Willett (who, incidentally is the great-great-grandfather of Coldplay lead singer, Chris Martin) who successfully campaigned in Britain to change the clocks, although his idea was a little more confusing.

In his pamphlet, The Waste of Daylight, he proposed clocks should be put forward by 80 minutes in four steps during April and reversed the same way during September. Thanks to his campaigning, British Summer Time was established by the Summer Time Act 1916, although he did not live to see the extra daylight he had fought for as he died in 1915. Are there plans to change BST? A Private Member’s Bill to put the clocks forward an hour was talked out by opponents in 2012 and did not come into law. But the UK has tried year-round BTS before. In 1968-1971, the British Standard Time experiment was introduced by the Harold Wilson government with Britain remaining on GMT +1 throughout the year. The result was a large reduction in road casualties thanks to the lighter evenings, but the experiment was ended due to complaints from northern parts of the UK, where mornings were darker as a result. Are there dangers to changing the clocks? Those lost 60 minutes of sleep could take their toll on some people. In the fortnight after the clocks go forward, the number of heart attacks increases, with a peak on the Monday morning immediately following the switch. Hasn't the European Union proposed scrapping Daylight Saving?

Yes, the EU voted to scrap the twice-yearly clock changes in 2019 although it is still awaiting approval from the Council of the European Union. Should it get ratified, EU states will decide whether to stay on permanent “winter time” or “summer time”.