Daylight Saving Time: A Ritual Worth Reassessing
This weekend, we will once again set our clocks back to adapt to winter time . We have been doing this for decades: every autumn and spring , we move the hands of the clock and shift an hour. However, this routine may be near its end . Spanish Prime Minister Pedro Sánchez has requested its abolition in Europe because it “no longer results in energy savings” and “disrupts circadian rhythms” twice a year.
This is not the first time the issue has been raised. “Attempts were made in the European Union before, and they did not succeed due to a lack of consensus,” recalls Carlos Egea , a pulmonologist and coordinator of the Sleep Disorder group of the Spanish Federation of Societies of Sleep Medicine (Separ).
Nevertheless, he celebrates the renewed discussion on this topic. “From a scientific standpoint, it is good news . For over a decade, we have defended that the human body needs to synchronize with natural sunlight each morning, and the healthiest approach is to maintain a consistent schedule.”
Scientific research supports this argument . Various studies indicate that avoiding time changes could reduce cases of insomnia, obesity, traffic accidents, and even strokes . A recent analysis from Stanford Medicine estimates that maintaining a permanent standard time could prevent up to 300,000 strokes and 2.6 million instances of obesity annually.
The Real Problem: Living Out of Sync
Why does something that “only” changes by 60 minutes affect us so much? Because the time change impacts a body that is already out of rhythm. Spain is one of the European countries that sleeps the least during the week . Staying up late, rising early, and dragging fatigue is common, resulting in compensatory oversleeping on weekends.
This habit has a name: social jet lag . “The sleep schedule from Monday to Friday rarely aligns with that of the weekend, disrupting the body. That’s why Mondays are particularly challenging,” explains Egea. When you add an artificial time shift to this imbalance, the body becomes even more disoriented .
“Even if it’s just one hour, the change incurs a cost to our organism . It disturbs sleep, alters melatonin secretion, and modifies cortisol levels. It may seem trivial, but it’s enough to throw us out of sync ,” asserts Francisco José Martín , a sports medicine physician specializing in cardiology.
The most affected individuals are the elderly and children . “Children already sleep less than they should during the week, and moving the clock makes it even more challenging for their bodies to adjust,” Egea specifies.
While adults may adapt in two or three days, the extremes of life could require up to a week . “Their biological clocks are more fragile, and any time change takes a toll,” adds the Separ spokesperson.
The simple reason is that changing the time also alters exposure to natural light . “The body has a central clock in the brain that requires light and darkness to know when to activate and when to shut down. Disturbing this rhythm affects our health,” he continues. So, which schedule best allows for the light that our body needs to function well ?
According to experts, the answer is clear: with winter time . It is the healthiest option as it aligns better with the natural rhythm of the sun. The days start earlier and end sooner, allowing our social clock (alarms, work, school) to synchronize with our biological clock governed by light and regulated in the brain. “We are diurnal animals. To function optimally, we require light in the morning and darkness at night. This is achieved best with winter time,” insists Egea.
If summer time were to be maintained year-round, in December, it would not be bright until very late. ” In some areas of Spain, natural light wouldn’t be visible until after half-past nine in the morning ,” he warns. This means waking up in the dark, commuting in darkness, and activating the body without the natural signal of light, disorienting our internal clock completely .
When this happens, the system doesn’t stop functioning, but it begins to do so out of sync. It’s as if the body follows one schedule while the external world follows another. The first thing to be affected is sleep: falling asleep and waking up becomes difficult, and even when sleep occurs, one wakes up exhausted. The sleep-wake cycle fractures .
Hormones also become unbalanced. Melatonin , responsible for sleep, is released at the wrong time; cortisol , which activates us in the morning, arrives out of order. Appetite alters as hunger-triggering hormones increase while those inducing satiety diminish.
The brain feels the shift, too. Concentration wanes and lapses occur, accompanied by that characteristic feeling of mental fog . Mood states also shift: irritability, apathy, or sadness may rise.
Can We Avoid This Misalignment?
Yes, but not with a pill. “The best treatment is free: sunlight,” Egea reminds us. Morning sunlight activates the brain, kicks in cortisol, regulates appetite, aids digestion, and prepares the body for the day. Therefore, going to bed early, respecting schedules, exposing oneself to natural light in the morning, and limiting screens at night are more beneficial than any supplement.
“This debate presents a good opportunity to reflect on our lifestyle : whether we dine late, use screens before bed, spend little time in the sun, or never find time to rest,” notes Francisco José Martín. The doctor questions whether what is best for the system is always what is best for health .
Martín details that daylight saving time was created for industrial and economic purposes : to make use of more daylight for labor and production. However, this perspective no longer makes sense or benefits the human body. “Performing optimally in industrial terms doesn’t equate to performing optimally for health. The industry’s drive for hyper-output is incompatible with human biology .”
“If we only think about working longer hours or 24-hour shifts, it might benefit the economy, but it disrupts the natural rhythms of the body and ultimately incurs costs on cardiovascular, metabolic, and mental health,” he warns. That’s why he welcomes the fact that the message doctors have been propagating for years is finally resonating with policymakers. “It’s promising that chronobiology is being considered in public decision-making,” he concludes.