It's that time of year again - the clocks will go back this weekend marking the official end of British Summer Time (BST). 

Between Saturday night and Sunday morning, we will gain an extra hour, meaning it will be lighter in the mornings but darker in the evenings. 

Clocks changes always take place on the weekend to try and limit disruption to everday life. 

Here's what you need to know about when the clocks will change, what time and why they go back...

When do the clocks change this weekend?

The clocks will go back in the early hours of Sunday October 31. 

They go back on the same weekend every year, with the change always taking place on the last Sunday of October. 

READ MORE: Does my iPhone automatically update the time?

What time will the clocks change this weekend?

The change to the clocks will come into effect around 2am on Sunday. 

It means we are reverting back to GMT, which stands for Greenwich Mean Time and is the standard time against which time zones in other areas of the world are measured.

Meanwhile, BST stands for British Summer Time and is the time zone referenced when the clocks go forward in spring. 

The BST is GMT+1 hour. 

Why do the clocks change? 

The principal reason we change the clocks is to get the most out of the daylight. 

The first clock change was introduced by the German government in 1916 during the first world war as a means of saving energy - the longer the daylight hours lasted, the less electricity required. 

Do we get an extra hour of sleep?

Yes! The good news about the clocks going back is we get an extra hour in the day - or an extra hour to sleep!

When will the clocks go forward in 2022?

The clocks might only just be going back, but you may already be wondering when they will go forward again...

We have a wee while to wait, with the next clock change scheduled for  March 2022, when they will go forward in order to make the most of the long hours of daylight.

Like in autumn, the change will take place on a Sunday to avoid too much disruption. 

Next year's change will take place on Sunday March 27 2022, marking the start of BST. 

The clocks going forward means we lose an hour, however we gain this back every autumn when they go back again.