Introduction
Twice a year, around a billion people groggily adjust their clocks — springing forward in March or April, falling back in October or November. Yet this ritual is far from universal. Fewer than 70 countries, well under 40 percent of the world, observe daylight saving time (DST) at all, and almost none of them are in Africa or Asia.
The map of DST is essentially a map of Europe, North America, and parts of the southern hemisphere's temperate zone. The rest of the world looked at the twice-yearly clock change, weighed the claimed benefits against the disruption, and opted out — or tried it and gave it up.
A Brief History of Daylight Saving Time
The idea is often credited to Benjamin Franklin, who in 1784 wrote a satirical letter suggesting Parisians could save candles by waking earlier — but he was joking, and he proposed cannons at dawn, not clock changes. The serious proposal came from New Zealand entomologist George Hudson in 1895, who wanted more evening daylight to collect insects, and from British builder William Willett, who campaigned for it from 1907 until his death in 1915.
Wartime made it real. Germany adopted DST on April 30, 1916, to conserve coal during the First World War; Britain followed three weeks later, and the United States in 1918. Most countries dropped it after the war, then readopted it during the Second World War and the 1970s energy crisis, when saving fuel again seemed urgent. That emergency measure, meant to be temporary, simply never went away.
Why Countries Opt Out
The most fundamental reason is geography. DST shifts an hour of daylight from morning to evening, which matters a lot at high latitudes where summer days are dramatically longer than winter days. Near the equator, day length barely changes across the year — roughly 12 hours every day — so shifting the clock accomplishes nothing. That is why almost all of Africa and most of Asia and South America skip it entirely.
Other opt-outs are political or practical. Arizona abandoned DST in 1968 because summer evenings in the desert are scorching, and residents wanted the sun to set earlier, not later; Hawaii left in 1967 because its tropical latitude makes DST pointless. Russia abolished the clock change in 2011, settled on permanent summer time, found the dark winter mornings unbearable, and switched to permanent winter time in 2014. Japan has never used it, and China — despite spanning five geographical time zones — runs the whole country on a single time zone year-round.
The Health and Energy Debate
The original case for DST was energy savings, and that case has largely collapsed. A 2008 US Department of Energy report found DST saved only about 0.5 percent of total electricity per day, and a study of Indiana's 2006 adoption found residential electricity use actually rose by about 1 percent — lighting savings were wiped out by extra air conditioning and heating. In a world of LEDs, air conditioners, and always-on devices, candles-and-coal logic no longer applies.
The health costs, meanwhile, have become clearer. Studies link the spring clock change to a roughly 24 percent spike in heart attacks on the following Monday, more strokes, more workplace injuries, and a measurable rise in fatal traffic accidents in the days after. The American Academy of Sleep Medicine formally recommends abolishing the seasonal change and adopting permanent standard time, arguing that standard time aligns better with the human circadian rhythm and morning sunlight.
What the Future Holds
The global trend is toward abolition. The European Parliament voted in 2019 to end seasonal clock changes by 2021, though member states deadlocked over which permanent time to keep and the plan stalled. In the United States, the Senate passed the Sunshine Protection Act in 2022 to make DST permanent nationwide, but it died in the House — largely over the health argument that permanent standard time, not permanent DST, is the healthier choice.
Dozens of countries have simply walked away: Russia, Turkey, Argentina, and most of Latin America have ended the practice in recent decades. The likely endgame is a world where each country picks one fixed time and sticks to it — leaving the twice-yearly clock change as a curious twentieth-century experiment that outlived its usefulness.
Sources
- Encyclopaedia Britannica — history, rationale, and global adoption of daylight saving time
- National Institute of Standards and Technology (NIST) — official US rules and background on daylight saving time
- Wikipedia — worldwide usage, controversy, and research on the effects of clock changes
FAQ
How many countries use daylight saving time?
Fewer than 70 countries observe DST, less than 40 percent of the world. It is used mainly in Europe, North America, and parts of the southern temperate zone, while almost all of Africa and most of Asia skip it.
Why don't Arizona and Hawaii observe daylight saving time?
Hawaii opted out in 1967 because its near-equatorial latitude means day length barely varies. Arizona followed in 1968 because an extra hour of blazing summer evening sun was undesirable in the desert heat. The Navajo Nation within Arizona does observe it.
Does daylight saving time actually save energy?
Barely, if at all. A 2008 US Department of Energy study found savings of about 0.5 percent of daily electricity, while an Indiana study found usage rose about 1 percent due to extra heating and air conditioning.
When was daylight saving time first used?
Germany and Austria-Hungary were the first to adopt it nationally on April 30, 1916, during the First World War, to conserve coal. Britain followed in May 1916 and the United States in 1918.
Is changing the clocks bad for your health?
Research associates the spring forward change with a roughly 24 percent increase in heart attacks on the following Monday, plus more strokes, injuries, and traffic accidents. The American Academy of Sleep Medicine recommends ending the switch and keeping permanent standard time.
About the Author
doyouknow.app Editorial Team — We reference government records, sleep-medicine research, and energy studies to explain why daylight saving time divides the world.
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