The UK's clocks change because of a 1907 pamphlet, a wartime coal shortage and a series of Acts of Parliament, the latest of which fixes the dates as the last Sunday in March and the last Sunday in October. British Summer Time was introduced in May 1916 to save fuel, briefly became permanent in 1968 and was abandoned again in 1971, and has followed the European calendar since the 1980s. For anyone who struggles with dark mornings, the history also explains the one thing the clocks cannot do: make more daylight.
Who first proposed changing the clocks?
A builder from Surrey called William Willett, who in 1907 self-published a pamphlet titled "The Waste of Daylight". His complaint was that Londoners slept through hours of summer sunshine in the morning and then lit lamps in the evening. His proposal, moving the clocks forward in spring and back in autumn, was debated in Parliament several times before the First World War and rejected each time. Willett died in 1915, a year before it became law.
Why did it happen in 1916?
Coal. In the spring of 1916 Germany introduced daylight saving to conserve fuel for the war effort, and Britain followed within weeks. The Summer Time Act 1916 received royal assent on 17 May, and the clocks went forward for the first time on 21 May 1916, returning to Greenwich Mean Time on 1 October. The measure was framed as a wartime economy, and it stuck.
What happened in 1968?
An experiment. From 27 October 1968 until 31 October 1971 the UK stayed on GMT+1 all year round, a period known as British Standard Time. Lighter evenings were welcomed in the south; darker mornings were not, particularly in Scotland, where sunrise in mid-winter drifted towards 10 am. In December 1970 the House of Commons voted by 366 to 81 to end the experiment, and the clocks went back in October 1971 for the first time in three years. The episode is the reason every later proposal for permanent summer time has run into the same objection from the north.
Which law sets the dates today?
The Summer Time Act 1972, which replaced the wartime legislation. Its original rule ran summer time from the day after the third Saturday in March to the day after the fourth Saturday in October. The March start was aligned with the rest of the European Community from 1981; the October end date followed in stages, with the clocks going back on the last Sunday in October from 1996, and the Summer Time Order 2002 wrote the permanent rule into the Act: summer time begins at 1 am GMT on the last Sunday in March and ends at 1 am GMT on the last Sunday in October, which is 2 am British Summer Time. GOV.UK publishes the dates each year.
| Year | Clocks go forward | Clocks go back |
|---|---|---|
| 2026 | 29 March | 25 October |
| 2027 | 28 March | 31 October |
| 2028 | 26 March | 29 October |
What does the clock change actually do to daylight?
Nothing. The number of hours between sunrise and sunset on a given day is fixed by astronomy, and the clocks simply decide what those hours are called. Going back in October moves the same daylight an hour earlier on the clock: the morning gets brighter and the evening darker. In London on 24 October 2026 the sun rises at 07:40 and sets at 17:48; on 25 October it rises at 06:41 and sets at 16:46. Nobody gained or lost a minute of light. When do the clocks go back in 2026? explains how to use the change to your advantage.
Why does it matter for winter mornings?
Because the argument has always been about who gets the daylight, commuters in the morning or everyone in the evening, and the body clock has a view. Bright light soon after waking is the strongest daily signal that sets it, and light late in the day pushes it later. The 1968 experiment gave the country bright evenings and dark mornings, and it was the mornings that made it unpopular. That instinct matches what sleep researchers have found since: for most people, morning light matters more. It is also why the recurring proposals to move the UK to permanent summer time draw the most opposition from Scotland, where mornings are darkest; winter sunrise times in Scotland shows why.
Frequently asked questions
Will the UK stop changing the clocks?
There have been repeated proposals, and in 2019 the European Parliament voted to end seasonal changes in the EU, a plan that had still not been put into effect at the time of writing. The UK has no current plan to change the rule; the GOV.UK page and the 1972 Act stand as they are.
Why does the change happen at 1 am and 2 am?
The Act specifies 1 am GMT for both changes. In March that is 1 am on the clock; in October, because the country is still on BST, 1 am GMT is 2 am BST, which is why the autumn change is usually described as happening at 2 am.
Was Britain on GMT+2 during the war?
Yes: British Double Summer Time ran in the summers of the Second World War, with clocks two hours ahead of GMT, as a further fuel-saving measure. It ended in 1945 and was used once more in 1947.
Does the clock change affect sleep?
The October change is a one-hour gain and most people adjust within a day or two. The March change costs an hour and can take a few days to absorb. Keeping a fixed wake time and getting bright light soon after it, from the sky or a lamp, is the standard advice for both; how to build a morning routine around a light therapy lamp covers the routine.
Where does this leave you?
With a clearer view of what the clocks can and cannot fix. They can shift an hour of daylight to the morning in October; they cannot lengthen a December day, and by mid-December the sun rises after 8 am in London regardless. For the weeks when the morning is dark whatever the clock says, a bright lamp at breakfast supplies the light the calendar cannot. When to start using a SAD lamp in the UK works through the dates, and the choose your light page compares DAYARC Rise and Mini.
About DAYARC
DAYARC is a new UK circadian rhythm startup. We make two bright-light lamps for the morning: DAYARC Rise (£199), a full-size lamp rated at 10,000 lux at approximately 30–36 cm, with four brightness settings, a 15 to 60-minute timer and adjustable height and angle; and DAYARC Mini (£49.99), a compact lamp rated at 10,000 lux at approximately 25 cm, with a folding stand that doubles as its cover. Both use UV-free LEDs and run from the mains. We publish plain specifications with the measuring distance, we do not make medical claims, and we write the DAYARC Journal to help people build a simple morning light routine around their own daily rhythm. You can read more about how we think on our approach page or compare the two lamps.
This article is general information, not medical advice. Check with a GP or qualified healthcare professional before using bright light if you have an eye condition, a condition affected by bright light such as bipolar disorder, or take medicines that increase your sensitivity to light. If you have persistent low mood or think you may have depression, speak to your GP. If you need urgent help, contact NHS 111, or call 999 in an emergency.
Sources
- GOV.UK: When do the clocks change?
- House of Commons Library: British Summer Time (research briefing SN03796)
- Royal Museums Greenwich: British Summer Time and daylight saving
- Summer Time Act 1972 (legislation.gov.uk)
- The Summer Time Order 2002 (legislation.gov.uk)
- Hansard, 16 July 1980: Summer Time (alignment of the March start date)