Summer time and solar time, advantages and disadvantages of the time change

In the night between Saturday 25 October and Sunday October 26, 2025 it will pass from summer time to standard time: at 03:00 all hands will be moved back one hour, to 02:00.

For years the question of summer time/winter time alternation has been on everyone’s lips, between those who would like to remove it at all costs and those who, instead, would prefer to keep it. While solar time can be considered as the“natural” timebecause it is linked to the passage of the Sun above the local meridian, summer time is instead one convention which involves moving the hands forward one hour during the spring-summer period to be able to make full use of the daylight hours.

The debate arises from the fact that changing the time allows for save energybut at the expense, according to some studies, of a potential impact on health. In fact, not all states in the world adopt summer time. After numerous discussions, the issue reached the European Union, which in 2019 expressed its opinion in favor of abolishing the time change: at the moment, however, a directive specifying how to set up a “fixed time” system at community level has not yet been approved.

Daylight saving time and standard time: when does the time change and what is the difference

THE’solar time, which in Italy comes into force every year onlast Sunday of Octoberis the timetable adopted in autumn-winter period and involves moving the hands back one hour. It is the time linked to the passage of the Sun above the local meridian – we could define it as “natural” time, in spite of the legal one which is instead linked to a purely energetic and work-related matter.

THE’summer timeon the other hand, comes into force every yearlast Sunday of Marchand it is a convention that involves moving the hands forward one hour. This is done during the spring-summer period to be able to make full use of the daylight hours, especially with regards to work activities: working with natural light allows you to save the energy linked to office lighting, for example.

Why daylight saving time was introduced and when has it been in effect?

In Italy thesummer time was first introduced in 1916with the aim of making the most of solar hours, reducing the waste of daylight and saving energy during the First World War, which was then underway.

In the following years, however, its adoption was not constant, alternating years in which it was suppressed and others in which it was reinstated: after approximately 20 years of uncertainty, in 1966 Law n.1144 decreed theofficial entry into force of daylight saving time in our country, with “normal time brought forward, for all intents and purposes, by sixty minutes”.

In the European Union, however, summer time has been officially in force in all member countries since 1996, when a common calendar was adopted.

The advantages and disadvantages of the time change

THE advantages of summer time, which involves moving the hands forward one hour, are different: energy first and foremost, but also environmental and cheap. As a reference, let’s take the 2025 data from Terna, the Italian company that manages the national electricity transmission network. Well, summer time has allowed us to save approximately 330 million kWh of energyi.e. a quantity equivalent to the average annual electricity consumption of approximately 125 thousand families. To this we must add the environmental benefits – i.e 160 thousand tons of CO₂ less released into the atmosphere – and the economic savings – equal to approximately 100 million euros.

Overall, from 2004 to 2024, thanks to summer time, Italy has saved a total of approximately 11.7 billion kWh: in monetary terms it is equivalent to the figure of 2 billion and 200 million euros! The months that allow the greatest savings are April and October because you can exploit natural light for longer. In summer this gain is smaller because the delay in turning on the light bulbs is linked to the evening hours, when work activities are already finished.

But if, on the one hand, saving in energy and economic terms has its importance, on the other, recent studies suggest a negative impact of the time change on human health.
One of the main problems is related to the alteration of circadian rhythm of our body (Roenneberg et al., 2019).

What does it mean? Let’s say that we all have an internal clock, capable of regulating the sleep-wake cycle. The time change messes up this clock, making us feel tired, distracted and sleepy, especially during the first day of the time change. But this is not the only problem. Other studies highlight how daylight saving time can negatively affect the number of heart attacks (Manfredini et al., 2018) and even on the number of suicides (Lins et al., 2020).

Will daylight saving time be abolished?

In February 2018 the European Parliament convened a Commission for amend the Time Change Directive. Numerous scientific studies have been analysed, especially regarding the impact on human health, and public surveys have been carried out to understand the will of European citizens. The response was strong, with 4.6 million responses and, of these, 84% were in favor of abolishing the time change.

The Commission vote took place on 4 March 2019 with 23 votes in favour, 11 against and 0 abstentions. What has been abolished, in reality, is not summer time itself, but rather the time change. Each country in the Union will be given the opportunity to choose whether permanently keep summer or winter time throughout the year, without the possibility of switching from one to the other as done so far. The deadline for the decision should have been the end of 2021, but the pandemic has certainly slowed down the decision-making process. 6 years after the vote, however, the EU has still not adopted any directive to establish how to set up a “fixed time” system at community level. For the moment, therefore, the alternation between summer time and standard time remains in force.