So when do the clocks go back this year?
Daylight Saving Time comes to an end this year at 2am on Sunday, October 31, early on the morning of Hallowe'en.
That's still over three weeks away from now but an easy one to pencil into the diary given it is one of the biggest dates in the calendar in Derry.
The 'fall backwards' in time serves an important practical purpose. It was originally devised as a way of maximising the best possible use of the daylight available to us during the winter.
When do the clocks go back in 2021?
The clocks always go back one hour at 2am on the last Sunday in October.
This year, the clocks will go back on Halloween, Sunday, October 31, 2021, allowing you an extra hour in bed.
The clocks going back means we are going back to Greenwich Mean Time (GMT), which give us brighter mornings and darker evenings.
Why do the clocks go back?
Putting the clocks back gives us an extra hour of daylight in autumn and winter.
We’re currently in Irish Standard Time (IST) or British Summer Time (BST) which means that when the clocks change on Sunday, October 31, 2021, we will move into Greenwich Mean Time (GMT).
In the summertime, early morning daylight was not being used as people slept, by moving the clocks forward in summer, we would get darker mornings but lighter, longer evenings.
The clocks then revert back to GMT in Autumn, as we set the clocks back an hour, for brighter mornings and darker evenings.