The clock change: why both fixed times come at a cost

The clock change is not perfect, but both fixed times come at a cost

Every October the same debate returns. And every October the same mistake is made: assuming there is a cost-free solution. In Girona, on winter time all year round, civil twilight in June would arrive around **4:38** and the Sun would rise at roughly **5:13**. In A Coruña, on summer time all year round, in the middle of December the Sun would rise at around **10:00**. Neither scenario is free. The first gives away sunrises nobody uses and brings darkness forward; the second forces children and workers to start their day in the dark for months.

The debate, however, usually stays at the level of clock anecdotes and never gets to the heart of the matter: **Spain has been on Berlin time** for decades, which means solar noon in Madrid falls at **13:13** and in A Coruña at **13:31** at the December solstice. The problem is not the clock change. The problem is the time zone.

The two fixed times and their numbers

The calculation is simple and damning. With permanent winter time, in June civil light in Girona would arrive at **4:38** and sunrise at **5:13**. That means most of the population would be asleep during the cleanest daylight hours of the day, and solar electricity would be generated when nobody needs it. With permanent summer time, in A Coruña the December sunrise would slip to **10:00**. Children would walk to school in the dark, and morning break would be their first contact with natural light.

Some argue that fixed summer time is better because the afternoon in the park is sacred. The argument makes sense: in winter, on standard time, kids leave school and it is already dark. But the American Academy of Sleep Medicine and other scientific societies back permanent standard time because it fits circadian rhythms best: early morning light synchronises the biological clock, while late afternoon light delays it. On summer time, children get up in the dark in winter and go to bed in daylight in summer.

The real cost of changing the clocks twice a year

The clock change is not free, but neither is it the catastrophe some describe. A meta-analysis by **Manfredini and others, from 2019**, covering seven studies and more than **115,000 people**, found that in the two weeks after the spring change heart attacks rose by around **5%**. After the autumn change there was no difference. It is small, but it is not zero. And it is not solved by calling anyone who notices it antisocial.

The alternative of making the change gradual —half an hour over two weekends a fortnight apart— sounds reasonable, but it is not without logistical problems: companies, transport and IT systems would have to adapt to two adjustments instead of one. The energy saving that originally justified the measure is disputed today, and most available studies suggest the effect on electricity consumption is marginal.

The time zone: the problem nobody wants to touch

The Government has already looked into it. In **2018** it set up a committee of experts, and its report of **March 2019** recommended not changing the time zone, arguing that the population had spent eighty years adapted to this time. On scrapping the seasonal change, the committee was inconclusive. Spain has two time zones: the Canary Islands run an hour behind, and nobody thinks that cuts them off from anything. Splitting the mainland is more complicated: it would miccionan deciding whether Madrid goes with Galicia or with Catalonia, and every company with its headquarters on one side and its factory on the other would have to live with two times.

Longitude does not go away; it governs solar noon. At the December solstice, the Sun is at its highest at **12:04** in Berlin, **13:13** in Madrid and **13:31** in A Coruña. That is why we wake up like Germany but eat dinner two hours later. The mismatch is not a whim: it is the consequence of sharing a time with Berlin.

What the evidence does not settle

The debate over the clock change has a deeper problem: there is no solution that pleases everyone. Fixed winter time is better for sleep but worse for afternoon leisure. Fixed summer time is better for the afternoon but worse for the biological clock. The seasonal change is an awkward compromise, but it is the only one that avoids the extremes. And the time zone, which is the root cause of the mismatch, remains the taboo nobody wants to tackle.

Meanwhile, every October the same debate will return. And every October someone will shout from the balcony because it is not natural. As if there were anything natural about a clock.