The EU on Friday urged member countries to work together to avoid turning Europe into a confusing patchwork of different timezones, after announcing plans to abolish seasonal clock changes.
The European Commission wants to end the longstanding practice of putting clocks forward an hour in the spring and back an hour in the autumn, arguing that it causes unjustified disruption.
Each EU country is being asked to decide whether it wants to stay permanently on what is now their summer or their winter time.
This will end the twice-yearly ritual of time changes but raises the possibility that neighboring countries such as Belgium and the Netherlands could end up an hour apart.
To avoid a mishmash of timezones in neighboring countries, the bloc's Transport Commissioner Violeta Bulc, who is leading the initiative, urged governments to cooperate as they make their choice.
"Member states now have to decide -- either they want to stick with summer or winter time," Bulc told reporters.
"In order to maintain a harmonized approach we are encouraging consultations at national levels to ensure a coordinated approach of all member states."
Commission President Jean-Claude Juncker announced the plan unexpectedly last month after an online consultation which generated some 4.6 million responses from EU citizens -- mostly from Germany, where the clock change is a major issue.
The proposal also raises a fresh Brexit conundrum: if it goes ahead, EU member Ireland will stop changing the clocks, but British-ruled Northern Ireland will continue the practice.
The British government said it has "no plans to change daylight saving time", meaning that for six months of every year, Ireland and Northern Ireland would be an hour apart.
Bulc did not give a clear response when asked about this issue but pointed to the fact the EU manages to "coexist" with three time zones at present.
Ireland's Minister for Justice and Equality Charlie Flanagan said he had taken note of the commission proposal.
"There are certain aspects and consequences for us in Ireland that will require careful and detailed consideration and therefore I will be listening carefully to the concerns of agencies and stakeholders," Flanagan added.
The plan still needs approval by the European Parliament and the 28 member countries but the commission, the bloc's executive arm, hopes to bring in the change as early as next year.
Many European countries began changing the clock seasonally in World War I to save energy, with the practice reinforced during World War II and during the energy crisis in the 1970s.
The practice has since been harmonized across Europe, with all Europeans advancing their clock by an hour on the last Sunday of March and putting it back an hour on the last Sunday of October.
Bulc said the energy-saving justification no longer applied, while commission Vice-President Maros Sefcovic insisted: "Brussels isn't micromanaging people's lives for the sake of it".