It happens twice a year and tonight will be its 100th anniversary.
Putting the clocks forward – if we remember – will herald the start of British Summertime and cost us all a precious hour’s sleep.
The annual “spring forward, fall back” ritual means it will be lighter in the evening and darker in a morning from tomorrow.
But why do we do it?
And what are the benefits?
Although daylight saving was first proposed in 1895 by builder William Willett, the great-great-grandfather of Coldplay frontman Chris Martin, it was only introduced in the UK in 1916.
With Europe in conflict, enemy Germany put their clocks forward on April 30 to save fuel for the war effort and Britain followed suit three weeks later.
But controversy has raged ever since, with proponents claiming it saves energy, promotes outdoor leisure activities, reduces road accidents and benefits the economy.
Opponents, including farmers, prefer lighter summer mornings and say the beneficial effects of daylight saving time have yet to be proven, a full century after it was first introduced.
In 2010, a private member’s bill was tabled in Parliament asking the Government to investigate going even further and putting the clocks forward another hour for all or part of the year.
It failed to get the support of MPs because of the adverse effect it might have on Scotland and Northern Ireland where the sun rises later than in England and daybreak would arrive as late as 10am.
The Royal Society for the Prevention of Accidents (RoSPA) is campaigning for a system which would see the time move ahead by an hour twice a year.
Its chief executive Tom Mullarkey said: “We firmly believe if we can collect objective data to show the benefits of Single/Double Summer Time to road accidents, we can change the minds of even the staunchest objectors.”
The official start of British Summertime is 1am Sunday.