How borders are drawn and enforced has far-reaching consequences, whether we live on either side of them or halfway across the world.

The UK enters British Summer Time (BST) on Sunday (March 29) at 1am, with clocks moving forward one hour. It’ll mean less time in bed that evening for millions of Brits, but longer daylight hours through the summer until the clocks get rolled back again in October.

It’s an annual event, but this year’s changes might be the last before things start to get really complicated. That’s because the European Parliament last year voted heavily in favor of ending Daylight Saving Time, meaning the bloc will no longer change the clocks twice a year starting in 2021. Each member state will get to decide whether to permanently set their clocks to BST or Greenwich Mean Time.

The UK would have had to go along with all that, had it not left the EU in January. Now it’s up to British officials to choose whether to maintain Daylight Saving Time. Brits appear to be more divided than their European counterparts, and officials have in the past suggested they don’t want to follow the EU’s lead.