ACHED Letter to the President of the Republic — France — 24 March 2025

A double blow to health and the climate

Please do not reply with a letter about “clock changes”, because that is not the primary subject of this letter. Yes, I mention them. With a clock change there is typically an advanced clock time. French people often experience the clock change acutely and consciously at least once a year, in March when the clocks move forward. They should certainly be listened to, but the whole problem must not be reduced to this part of the subject.

ACHED’s mission is to end UTC+2 in France and, secondarily, to end clock changes. Our original name was Association Contre l’Heure d’Été (DOUBLE), for the reduction of clock advancements. Notice the word ADVANCEMENT.

The more fundamental issue is the advancement of clock time relative to Greenwich Mean Time, whose meridian crosses France. It is convenient to speak of time zones. France’s natural time zone, like England’s, is therefore UTC+0 [Annexes]. The other zones to which we are assigned are “artificial” time zones. They no longer even have a genuinely geometric spindle-like shape; they are simply “time zones”.

Please consider the figures we are about to present. The totals can easily be consulted in the annexes as infographics, especially [Appendix 3]. This appendix will accompany our press releases relating to this letter. Have such figures ever been mentioned to you? In any case, you will not find them in the press or in official reports.

This is a counterpoint to the information circulating in the media, based on serious and documented sources; hence this letter, with around 20 pages of bibliographic references accessible by clicking in the PDF [REF].

These totals are fully consistent with the messages we have conveyed since our founding in 1983 and especially since I became president, but here we have brought them together and they are VERY SIGNIFICANT, not minor at all. We believe their magnitude should move you to act.

For practical reasons, we would like a public or written response to this letter; please also notify us by email.

A press release will coincide with the sending of the letter and there will be at least an English translation. Our association has existed since 1983. We held a public-interest label. We have interacted with every French president since 1983, so far without success, while accumulating expertise that did not disappear with the deaths of our first two presidents, Dr Boris Sandler and my late mother Leonor Gabarain-Echevarria [25].

We have sent you several letters, some of which you answered, first as a candidate in 2017 — unfortunately I have not found the copy — and later as President during your first term.

With the current system, you are delivering a double blow to health and the climate. This began before your presidency, in 1916 with clock changes. In 1945 General de Gaulle did not put an end to it; he did not maintain the clock change, but the country was placed on permanent advanced time, UTC+1 [26]. May he rest in peace; science was not as advanced, but French people did not appreciate it at all.

You will not find this in newspapers, but older generations told us. The mistake was compounded in 1976 by an additional one-hour advancement [35], as if no one had noticed that we were already one hour ahead.

But since 2017, responsibility now lies with you. Worse still, you have been actively or passively involved in the idea of ending clock changes while keeping UTC+2 all year round. That would mean a two-hour advancement WITHOUT clock changes.

That would be a mistake, an even greater double blow to health and the climate, which we ask you not to make.

As for the status quo, let us be clear: not only do clock changes make French people suffer in a way they consciously experience, but the health and climate problem is being exacerbated by a rapidly worsening climate context [62].

It is time to grasp the seriousness of the situation and show responsibility towards both the climate and public health.

Carbon emissions and time zones: a connection too often ignored

• Damaged health: darker mornings and overly bright evenings → shorter sleep and reduced well-being.
• General overconsumption linked to deteriorating health and shorter sleep.
• Higher carbon emissions: general overconsumption; more heating in the morning and air conditioning in the evening; more car use morning and evening.

With UTC+1 or UTC+0, we would save several billion euros per year in health spending alone — €7 billion annually according to our estimate [43] — which would directly reduce carbon emissions, using a ratio of 111 gCO₂/€, by around 777,000 tonnes of CO₂.

Health expenditure includes poor health promoted by clock advancement, as discussed by chronobiologists [18]. It also includes workplace and everyday-life accidents [W].

The supposed lighting savings under daylight saving time, with clock changes, around €70 million per year [30c] according to ADEME’s 2010 report [30][30a][30b], are more than offset.

Please note that we are referring to a report still regularly cited in the French press and still the only reference provided by ADEME nearly 15 years later, while the report and summary are no longer available online except through web archives.

With UTC+1 or UTC+0, France could potentially emit one or several tens of millions fewer tonnes of CO₂, as briefly explained below. See also [Annexes].

These potential savings under UTC+1 or UTC+0 are, under the current system, additional costs and emissions, which would increase further under permanent UTC+2.

With UTC+1 or UTC+0, sleep duration [H] naturally increases compared with UTC+2. Conversely, we have lost 1 to 1.5 hours of sleep — 14–20% — in 50 years. People slept up to 9–10 hours at the beginning of the twentieth century, below 9 hours in the 1950s, below 8 hours in the 1970s and below 7 hours in the 2000s.

When we sleep, we consume less. So under UTC+1 or UTC+0, imagine a 10% increase in sleep and a corresponding reduction in consumption gradually appearing.

Since we are awake for roughly twice our sleeping time, and national emissions are estimated at around 400 million tonnes CO₂-equivalent, a 5% reduction would mean 20 MtCO₂; even 2% would mean 8 MtCO₂.

With better sleep there are fewer suicides [I] [21] [22] [19.7]. The introduction of double daylight saving time in the 1970s coincided with a significant increase in France’s suicide rate, which our association noticed at the time.

Coincidentally, Belgium also experienced a major increase in its suicide rate with a one-year delay, and Belgium adopted our time system exactly one year later. Under UTC+1 or UTC+0, a reduction in suicides is plausible, all other factors being equal.

Regarding heating and air conditioning, the 2010 ADEME report (Énergies Demain) modelled 2030 and announced uncertain and minimal savings with the current system compared with permanent UTC+1 [30b].

Savings for some came at the expense of others, combining residential and tertiary sectors: residential uses more air conditioning, while the tertiary sector uses more heating. The residential heating savings produced by modelling were not very credible.

Overall [30a][30b], the ADEME report announced savings of 440 GWh in lighting in 2009 and 470 GWh in lighting, heating and air conditioning in 2030, with around 70,000–100,000 tonnes of CO₂ in 2030, including about 30,000 tonnes from lighting.

Other studies, however, showed clear overconsumption [40][42] in both air conditioning and heating in the residential sector, leading us to estimate an increase of 558,600 tonnes of CO₂ in a 2019 letter [42a].

A common argument for daylight saving time is the reduction of the evening electricity peak. But the evening peak is broad, while the morning peak — no less important — is intensified [30d].

ADEME did not examine increased consumption caused by sleep loss, fuel overconsumption or the impact on the electricity grid of Germany and France being on the same clock time, except for a brief mention of car air conditioning [page 69 of the final report].

As early as the 1990s [42], it was already known that advancing the clock to UTC+2 was associated with increased leisure car traffic.

The additional Belgian traffic observed by Walter Hecq [42a] alone represented more than 111,000 additional tonnes of CO₂. For France, using the Belgian data, we calculate 388 kt of CO₂.

This does not include the impact on morning and evening traffic, which has not been studied in relation to chronic clock advancement except in accident studies. It is, however, widely accepted that clock changes increase accident risk.

There is also a dimension of savings / overconsumption / emissions that appears neither in ADEME’s report [30][30a][30b] nor in our 2022 ACHED contribution [8b], because it lies somewhat outside a purely national perspective.

In early 2023 in Metz, if memory serves, we met an RTE representative. The issue concerns savings that cannot be achieved because France and Germany are on the same clock time [8c] and [Appendix 4].

ADEME did not examine the effect of winter clock advancement either, in particular the possibility of UTC+2 in winter, because the report was intended to justify the 1976 advancement.

For further details on the ADEME report, we refer you to our letter formally requesting its retraction [30e].

To summarise, potential savings under UTC+1 / UTC+0 amount to around €7 billion per year in health spending, while emission reductions total 777 + 588 + 388 = 1,753 kt CO₂ = 1.7 MtCO₂, and potentially much more (20 MtCO₂?).

This is far from negligible when the 2030 objective requires reducing our emissions by around 126 Mt between 2022 and 2030 [14].

These savings and emission reductions under UTC+1 / UTC+0 become additional spending and additional carbon emissions if we maintain the status quo, and even more if we adopt UTC+2 all year round.

Listen to civil society and science

We ask you to listen to:

• The majority of French people, tired of clock changes [48].
• The signatories of the #RetourVersLeFuseau petition, and all citizens and associations committed to a fairer and more sustainable time [1].
• Sleep and biological-rhythm scientists, who advocate a return to a more natural time, closer to solar time [18][19].
• Experts [70], climatologists [68][69][72][73], agronomists and agroclimatologists [67], who warn that warming is taking us towards unsustainability.

Conversely, beware of lobbies [45][45a][45b][45c] that benefit from overconsumption, uniform time zones or disinformation: oil interests, the automotive sector, media and even certain foreign interests.

Beware of those who misjudged the impact of clock changes / clock advancement, or believed in it, or see advantages in it and do not want to change their minds.

We also ask you to support:

• Citizens living near borders, for whom uniform time zones can be convenient but at the expense of health and overall emissions.
• Those who have only known double daylight saving time and need help adjusting their habits and reference points towards a more balanced time [55].

Biased consultations, questionable studies and abusive or negligent situations at French and European level

We challenge:

• The European report EU summer-time arrangements under Directive 2000/84/EC [31][31a].
• The 2010 ADEME study Impact du Changement d’heure [30]…[30e].
• The European Parliament resolution of 26 March 2019 [39].
• The public consultations of 2018 by the European Commission [46] and 2019 by the European Affairs Committee of the French National Assembly [48].

We are not alone in denouncing the partial, biased or sloppy nature of these consultations [50][51][52][53][54].

We believe these studies and reports did not provide the public with satisfactory information or allow genuine democratic debate. Some are no longer even available online, although they continue to feed media coverage.

Most media simply relay press-agency releases, themselves sometimes written carelessly, complacently or wearily, without verification or critical scrutiny.

These are the reports that feed climatologists and energy specialists with misinformation and confusion. We were not listened to for the Citizens’ Convention, where citizens were supplied with these reports.

Our February 2022 ACHED contribution to the low-carbon strategy [8b] was ignored, and we remind you that you did not answer our letters referring to it [11], [12], [3].

We are also surprised that several major European reports are not officially translated into French [31], unlike Council of Europe publications [37].

For citizens and elected representatives who do not master English or German, transparency, scientific truth and democracy are directly threatened.

Automatic translation is certainly a useful tool — and we use it — but it consumes energy and time and is not accessible to everyone. For documents this sensitive, competent human review is required because errors and mistranslations are frequent, especially on a technical subject such as legal time.

All cited documents should also be available, preferably in French, or at least with a summary. French documents such as the 2010 ADEME report and earlier reports should be easily and freely accessible to citizens and at least to associations.

Let us repeat: reducing the problem to clock changes is a frequent and misleading presentation.

It is surprising that the European Parliament legislates on clock changes [Q], because clock changes themselves are not an EU competence; only harmonisation of the dates is.

It makes even less sense if Europe deals only with clock changes while allowing countries to choose their legal time independently and without a clear recommendation.

In fact, only one solution should be on the table: a return towards the natural time zone, initially to what is commonly called “winter time”.

On health, thanks to chronobiologists speaking out and to the work of associations, parliamentarians are increasingly informed about the health harm. But what about the energy and climate harm described here?

We regret the inaction of the French Parliament and government after the 1997 parliamentary work Faut-il en finir avec l’heure d’été ? [28], repeated after the Council of Europe report and recommendation in 1999 [37].

Those studies were of good quality and already highlighted the double problem of clock changes and clock advancement.

Given the research [G] available following scientific and medical progress in biological-rhythm science — recognised by the 2017 Nobel Prize — as well as key energy studies in 2003 (Kellogg) [40], 2009–11 (Kotchen) [41], and a 2019 socio-economic study of time zones (Giuntella and Mazzonna) [44], this is unacceptable.

Even Russia’s 2011–2014 experience [33c][33d][33e] and [18] should enlighten everyone: Medvedev’s Russia stopped clock changes in 2011 but initially made the mistake of choosing permanent summer time; Putin ultimately granted permanent standard time.

It is abusive [45][48] to propose advancing the clock even further when the earlier move to UTC+1 without clock changes from 1945 to 1975 had already caused dissatisfaction, and scientists and economists clearly say that clock advancement is bad for health, reduces sleep and increases consumption.

No energy / environmental / climate study has been carried out specifically for advanced time in winter [39][45][48].

Researchers are nevertheless clear that under advanced time, extra heating consumption is greater than lighting savings and that shifting activity towards darker, colder mornings causes substantial overconsumption [40] and page 19 of [41].

What we ask for

We support and want to strengthen:

• Health, retirement and quality-of-life objectives for the French population.
• Ambitious objectives for reducing our emissions.
• The idea that “the best adaptation to +4°C is NOT TO REACH +4°C”.

We ask you [1] to act quickly to:

• End clock changes.
• Adopt a permanent time closer to solar time.

France has the means to set an example in Europe. The time has come to choose the right time zone: for health, climate and the immediate and future quality of life of citizens. The status quo is an avoidable mistake.

In practical terms, we want our contribution to the low-carbon strategy to be reflected in SNBC communications [14] and incorporated into the PPE [16]. We want ADEME to publicly withdraw its 2010 report [30e].

Please verify our calculations; we can make mistakes, but do not use that as a reason to delay indefinitely. The key is not to leave anything out, but to cover the whole picture and fit the parts together.

We want you to mobilise your advisers and help mobilise experts [59][67], newspapers, ministries [9a][9b][3], committees [60], academies and professional orders in the health, energy, climate, environmental and social fields.

Please, no demagogic consultation. We want democratic participation, not noise and disorder. Do not let lobbies overwhelm the process.

Polls should also educate and measure knowledge before collecting opinions.

We believe the French effort is important and can be transmitted to Europe [8c] as well as to the United Nations [17]. The ball should not simply be passed to European institutions [75].

They have only tentatively included the issue in their 2025 programme [40a], which is not reassuring. They pass it back to you anyway, so embrace the subject.

French studies such as those by ADEME, RTE and others should take greater interest in the positive interactions of #RetourVersLeFuseau [8c].

French legal time belongs to us perhaps more than to others. We should use it wisely, share with other countries and make amends.

It was France that started the domino effect of daylight saving time in continental Europe in 1976, by decree [35]. The European Union intervened only to harmonise clock-change dates [38][25].

It is our French ADEME 2010 report [30], and those of earlier bodies, that poisoned European [37] and global reports. Retract this report and it will be easier to put things right.

President Zelensky and conclusion

As you are in regular contact with President Zelensky and are due to meet him on Friday 28 March, on the eve of the clock-change weekend, we invite you to support him in ending clock changes and choosing standard time, as voted by his parliament and awaiting approval.

You can find here the French translation of the letter we sent him: lettre20250320VZ.pdf [33][33a][33b].

Abolishing a clock change is unquestionably simpler than introducing one. Historically, the population adapted — at least in practice, even if with damage — to the abrupt introduction of daylight saving time in 1976.

With the knowledge now established about the health and climate benefits of returning to a more natural time, it is your responsibility to accompany, inform and explain.

As James Clear argues in Atomic Habits (2018) [66], small improvements accumulated over time can produce major long-term results. Ending clock changes and returning to a more natural time is exactly that kind of change.

Even if some businesses fear an adjustment in revenues linked to current schedules, the transition would be gradual and offset by gains in public health, energy sobriety and climate stability.

This is precisely what we need to slow climate destabilisation and limit extreme events.

Many countries also have several time zones and function perfectly well: Canada, the United States and Russia. Are we really saying that French people could not work with their European neighbours because of a one-hour difference?

I appeal to the President who inspired us with the call “Make the Planet Great Again” [74].

Hoping that you will rise to the scale of these challenges, please accept, Mr President of the Republic, the expression of our highest consideration.

For ACHED, its President,
Laetitia Moreau-Gabarain
Agricultural engineer