Every year in Spain, the clocks go back an hour during the early hours of the morning on the last Sunday in October.
Thus, at 3am tomorrow morning (Sunday 30th October) the clocks will go back to 2am and an extra hour's sleep will be up for grabs.
People in the Canary Islands make this change an hour earlier on their clocks, but at the same time as mainland Spain, so that at 2am on their clocks it will be 1am again.
The clocks are changed twice a year in Spain - they go forward an hour in the spring and back an hour in the autumn.
Historically, the clocks were changed so that labourers, especially farm workers, could make the most of the natural light and thereby save energy. There are many who believe that this change is now unnecessary and who argue that the clocks do not need to be changed at all.
Then there are others who believe that Spain should be on the same time zone as Portugal and the UK, i.e. an hour behind official Spanish time. Up until 1940, Spain used the same time zone as the UK and Ireland, but after the Civil War and a dictatorship more aligned with Berlin and Rome than London, it was established that Spain would use Central European Time.
Although only Catalonia and the Balearic Islands are east of Greenwich, only the Canary Islands currently use Greenwich Mean Time (GMT) - which is now referred to as Coordinated Universal Time or Universal Time Coordinated (UTC).
