What Is Daylight Saving Time and Why Do Clocks Change?
What is daylight saving time, who came up with it, why clocks fall back in October and November, the 2026 dates for Europe, Egypt and the US, and who skips it.
Every autumn, millions of people search for the same thing: “when do the clocks go back?” But what is daylight saving time in the first place, who thought it was a good idea, and why do some countries ignore it completely? Here’s the whole story in plain language.
What is daylight saving time?
Daylight saving time (DST), called “summer time” in the UK and much of Europe, means moving the official clock forward by one hour in spring and summer, then back again in autumn to return to standard time (often called “winter time”).
In summer the sun rises very early, so an hour or more of morning light is “wasted” while most people sleep. Moving the clocks forward shifts that hour of daylight from the early morning to the evening, when people are awake and out of work or school.
Changing the clock doesn’t make the day any longer or shorter, of course. Day length depends on Earth’s tilt and its orbit around the Sun; clock time is simply a human agreement.
Who invented daylight saving time?
Benjamin Franklin often gets the credit, but his famous 1784 essay was a joke suggesting Parisians get up earlier to save candles. He never proposed changing the clocks.
| Year | Milestone |
|---|---|
| 1784 | Franklin’s satirical essay about rising early to save candles |
| 1895 | New Zealand scientist George Vernon Hudson proposes shifting clocks in summer |
| 1907 | British builder William Willett publishes his pamphlet The Waste of Daylight |
| 1916 | Germany becomes the first country to adopt DST, during World War I, to save fuel; Britain follows weeks later |
| 1918 | The United States adopts daylight saving time |
Did you know? William Willett, the idea’s best-known champion in Britain, died in 1915, just one year before his country finally put the clocks forward.
Why do countries change the clocks?
The original reason was saving energy: lighter evenings meant less need for artificial lighting. Other arguments often made for DST include:
- more usable daylight after work for shopping, sport and leisure
- fewer people travelling home in the dark
- keeping schedules aligned with trading partners that use the same system
Today, though, the energy savings are debated by researchers, because the way we use electricity has changed a lot (air conditioning, screens and devices). That’s why several countries and regions keep discussing whether to scrap the twice-yearly change.
When do the clocks go back in 2026?
Dates vary by country. Here are some of the main “fall back” dates this year:
| Region | Clocks go back one hour |
|---|---|
| European Union and UK | Early Sunday, 25 October 2026 (at 01:00 UTC) |
| Egypt | Midnight at the end of Thursday, 29 October 2026 (12:00 becomes 11:00 pm) |
| Most of the United States | 2:00 am on Sunday, 1 November 2026 |
In the week between 25 October and 1 November, the time gap between London and New York shrinks from five hours to four.
In Egypt, the rules are set by Law No. 24 of 2023: summer time starts on the last Friday of April and ends at the end of the last Thursday of October. In the US, Hawaii and most of Arizona don’t change their clocks at all.
Most smartphones update automatically if automatic date and time is switched on; wall clocks and older devices need changing by hand.
Countries that don’t change the clocks
Most countries near the equator don’t bother with DST, because day length barely changes through the year. In the Arab world, Saudi Arabia and Qatar don’t use it, and Jordan and Syria announced in October 2022 that they would stop switching their clocks twice a year and keep one time all year round.
Does changing the clocks affect your health?
Many people feel tired or sleep a little badly for a few days after a clock change, because the body’s internal clock needs time to adjust. A few simple habits help:
- shift your bedtime by about 15 minutes a day in the days before the change
- get some morning sunlight, which helps reset your body clock
- keep regular sleeping and waking times
For more on rest, read: How much sleep do you really need?
Frequently asked questions
What’s the difference between daylight saving time and standard time?
Daylight saving time moves the clock one hour ahead during the warmer months. Standard (winter) time is the normal clock, restored by moving it back an hour in autumn.
Do clocks go forward or back in winter?
They go back one hour, so you get an extra hour in bed on the night of the change. The easy rule: “spring forward, fall back”.
Which country used daylight saving time first?
Germany, on 30 April 1916, during World War I, to save coal and energy.
Will my phone change the time automatically?
Usually yes, as long as automatic time is enabled and the system is up to date, because operating systems carry the time-zone rules for each country.
Key takeaway
Daylight saving time is a century-old idea for moving an hour of daylight from the morning to the evening. Germany introduced it first in 1916. Europe, Egypt and the US still switch twice a year, while many other countries, including several in the Arab world, keep a single time all year. In 2026, Europe falls back on 25 October, Egypt on the night of 29 October, and the US on 1 November.
