There could be two time zones on the island of Ireland from October 2019, under a proposal announced yesterday by the European Commission.
The proposal, announced by Commission President Jean-Claude Juncker in his State of the Union Address, would end the tradition of member states alternating between summertime and wintertime every year.
Under the plan, which requires the approval of the European Council and the European Parliament, the last mandatory change to summertime would take place on Sunday 31 March 2019.
Member states would then be required to choose whether to permanently remain in summertime or wintertime.
Those choosing to remain in wintertime would make one final clock change at the end of October 2019.
However, Britain, which is due to leave the European Union on Friday 29 March 2019, would continue to change between Greenwich Mean Time and British Summer Time every year.
A British government spokesperson told RTÉ News: "The UK Government has no plans to change Daylight Saving Time."
As a result if the European Commission proposals are enacted, there would be a one-hour time difference either side of the border for part of the year, from as early as the end of October 2019.
Depending on whether Ireland chooses to remain in summertime or wintertime, the one-hour time difference would run from the end of March to the end of October, or from the end of October to the end of March.
Read more: Saving daylight - How Ireland embraced summer time
Fianna Fáil’s Brexit spokesperson Lisa Chambers has said a situation where there are different time zones either side of the border is "totally impractical".
"I would hope that with something like this there would be a common sense approach and no time difference on the island," she said.
"This is precisely the kind of thing that could get lost in the noise of the other, bigger Brexit issues to be resolved and while most people will laugh at the suggestion of such a time difference on the island of Ireland, it would not be funny if it were to actually transpire."
Sinn Féin has said the issue needs to be factored into the withdrawal agreement being negotiated between Britain and the EU.
David Cullinane, the party’s Brexit spokesman, said: "A ludicrous situation is now developing where there may be two time zones on one small island."
Yesterday, a spokesperson for the Minister for Justice, whose department oversees the bi-annual time change, said Charlie Flanagan had an open mind on the issue.