Why do the clocks go forward and what impact does it have on your health?

The clocks go forward on Sunday, marking the beginning of British Summer Time (BST).

This marks the end of Greenwich Mean Time (GMT) and will mean longer, lighter evenings from next week.

But besides losing an hour of sleep, the positive and negative impacts of daylight savings are hotly debated.

Here is everything you need to know about why and when the clocks go forward, as well as the impact on your body.

When do the clocks go forward?

The clocks go forward at 1am on the last Sunday in March. This year that will be on March 30.

BST – or daylight saving time (DST) – lasts until the final Sunday in October, when the clocks go back an hour.

– What does it mean for our sunlight?

Early risers will notice darker mornings immediately after the March change, while evenings will be lighter as the sun sets later.

As sunrise and sunset times continue to extend, parts of the UK will see almost 19 hours of daylight by the summer solstice on June 21.

What is the difference between British Summer Time and Greenwich Mean Time?

GMT was the default legal time used in Britain before DST was introduced.

This means when the clocks go back, the country returns to the default time zone introduced in Britain in 1880.

When was DST introduced?

Contrary to popular belief, the time jump was not introduced to benefit farmers. In fact, farmers were never consulted.

Several dairy farmers have complained that the change disrupts their schedule, unsettling cows which struggle to cope with the schedule change.

In Britain, DST was first proposed by inventor William Willett in 1907.

He published a pamphlet called The Waste Of Daylight, which outlined his frustration with not getting the most out of summer days.

He initially proposed that clocks jump forward by 80 minutes in four steps in April and reversed the same way in September.

He died before any law was implemented in the UK, but his great-great-grandson, Coldplay singer Chris Martin, has seen it in action.

The first country to adopt DST was Germany in 1916, during the First World War. The UK followed suit a few weeks later.

What are the benefits of the clocks going forward?

Dr Jeffrey Kelu, circadian rhythms expert at King’s College London, says there can be a number of arguments for DST.

He told the PA news agency: “I think there are some suggestions that there is less crime because more people are out there in the evening and it is harder to commit crimes.

“Also there are fewer traffic accidents because there is more light and people can see the traffic conditions more clearly. But there are conflicting studies.”

People are also in favour of clocks going back due to the increased daylight in the morning, which can lead to higher levels of productivity.

What are the negatives?

Dr Kelu said: “The circadian clock regulates our physiology and metabolism, and we know that extreme cases such as shift working, causing circadian misalignment, will lead to increased risk in metabolic disorders such as obesity and diabetes.

“We believe that even for daylight savings time, the changing of the clock would be affecting health in some sense.

“The most acute effect would be the loss of an hour of sleep and also the inability to adapt to the new working schedule. So the scientists and communities, as well as the sleep experts, actually suggest removing daylight savings as a whole.”

What can you do to prepare?

Dr Kelu suggests gradually changing the time you go to sleep in small increments in the days leading up to DST so it has less of an impact.

He said: “Because we cannot change the daylight saving time now, the thing is we can slowly prepare for it even though there’s not many days left.

“But we can slowly adjust to it by changing your clocks, for example, 15 minutes, 30 minutes, 45 minutes, until the hour changes.”

Should daylight savings time be abolished?

YouGov’s most recent poll, published in October, showed that if our current system were scrapped, 59% of Britons would opt for the country to stay permanently on BST.

Alex Mayer, Labour MP for Dunstable and Leighton Buzzard, has called for a “major overhaul of time” and a conversation about “how best to use our nation’s daylight hours” in a parliamentary debate.

She said a return to what is known as “Churchill Time” used during the Second World War – when clocks moved an hour ahead in winter and two hours ahead in spring and summer – could help save a combined £485 million in yearly electricity bills, and reduce carbon emissions by more than 400,000 tonnes.

Dr Kelu said: “I think the UK Government has not seriously conceived or actively discussed scrapping daylight savings but there is some discussion happening in the EU, and the States are also trying to pass a law to remove the daylight savings time.

“But the more complicated thing to follow would be which time do we use if we remove daylight savings time.

“From scientific evidence, we actually recommend sticking with the standard time, which would be GMT in the UK.

“We think that the morning light is the most important because the morning light will be required to synchronise your body clock with the environment. So after balancing all this scientific evidence, we think that keeping the morning light would be more important and beneficial to health.”

US President Donald Trump posted in December that he wanted to scrap DST. His secretary of state Marco Rubio has also called the ritual of changing time twice a year “stupid”.