Sleep researcher Ferran Barbé, in a provided image.
Like every last weekend in October, the Spanish are turning their clocks back one hour this Saturday, the 28th. At three o’clock it is two o’clock and the dawn and dusk are correspondingly earlier. Although the majority of Spaniards agree with ending this jet lag that occurs twice a year – the other time at the end of March – there is no consensus between scientific opinion and the general population on what schedule to follow. Two out of three citizens like the summer version more, while the winter version generates a majority consensus among health experts. This second group includes Ferran Barbé (Alguaire, Lleida, 1961), professor of medicine at the University of Lleida and, according to the journal Sleep and Breathing, one of the most influential researchers on sleep issues. Barbé attends EL PAÍS from her office at the University Hospital of Santa Maria in Lleida via video call, in which she advocates maintaining “a fixed schedule” throughout the year and making it the “winter schedule”.
Questions. How does the time change affect health?
Answer. On an individual level, the change in schedule has negative effects on attitude, character, ability to concentrate or sleep quality. It is estimated that the effects typically last between about three days and a week. So there is no need to dramatize it, but the consequences are there. There are various studies that link the time change with an increase in cardiovascular problems and even traffic accidents, especially when the daylight saving time change takes place, which costs an hour of sleep. This is because we are adapted to a rhythm of light and dark that helps us release melatonin. [hormona que regula el sueño] and when it suddenly stops working properly, we lose the ability to fall asleep.
Q And why is winter preferable to summer?
R. Because of the biological clock. Waking up and starting the workday with sunlight, as will be the case starting this weekend, causes melatonin to disappear and helps us be more active. And the same thing happens in the afternoon; The longer the daylight hours become, the longer it takes for the hormone to be released. In addition, the time change was introduced in 1974 for economic reasons related to the oil crisis. However, there is currently no evidence that greater energy efficiency can be achieved.
Q The time changes until October 2026 have already been published in the state gazette. Will this be the last year?
R. It’s likely, but not official yet. In the European Union there is consensus not to produce them since 2018, but in Spain it has not yet been decided which one to keep.
Q How do you explain that 66% of Spaniards prefer summer?
R. Social life, community life is highly valued. Starting next week, when it gets dark around six in the afternoon, people will have less desire to make leisure plans. And then there is the question of the word with which we define each of the schedules: the summer schedule is associated with calm and more good vibes, while the winter schedule is associated with cold and darkness… Estrella Damm makes no announcement in winter [entre risas].
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Q Which population groups are most affected?
R. Children and the elderly are more vulnerable. The former because they need more hours of sleep and the latter because they are generally more vulnerable. However, it must also be noted that one hour less sleep becomes more noticeable during the change of spring.
Q What other factors change sleep routines besides schedule?
R. Light stimuli from any device such as computers, cell phones or tablets, a large dinner or exercise in the three hours before going to bed are factors that do not promote the release of melatonin. Also the temperature or outside noises. All of these problems cause insomnia, which affects almost 10% of the population and interferes with good sleep. And these problems are paid for by health: increased risk of high blood pressure, diabetes, cardiovascular diseases…
Q Is sleeping very frowned upon in society?
R. It seems that sleeping is synonymous with laziness. But we all have a biological sleep clock that is genetic and unchangeable. Everyone’s needs are different, ranging from four or five hours to eight or nine hours. And we have to respect them if we want to be productive.
Q Is there a deregulation of sleep in Spain due to the time zone to which we are assigned, namely that of Central Europe?
R. Deregulation occurs because we would have to eat at one o’clock and have dinner between seven and eight o’clock. However, since this clashes with commercial activities and social habits, the change would have to be global. It doesn’t make sense that we have the same time as in Prague.