Do this one simple thing before you go to bed and ‘earn’ £280 a year!

What if we told you there was an easy way to earn yourself £280 a year? And when we say easy, it's as simple as flicking a switch? Just think what you could spend the extra cash on. There's only one drawback – and that's if you're afraid of the dark.

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So what is this magical money spinner, we hear you ask? Well, if our clue didn't help, we'll fill you in. It's turning off the bedroom light. A new survey from homeware and furniture retailer Utility Design has revealed that the cost of leaving lights on while we're asleep is an incredible £1.32 billion. That equates to wasting £0.77 for every eight hour's shut eye, £23.42 a month and £281.05 a year.

The research found that an estimated 4.7million leave at least one light on overnight, unnecessaril. And increased energy bills aren't the only side effect. Not flicking the switch to off is creating 8,985,600kg of extra carbon dioxide emissions. That's the equivalent of 15 round-the-world flights.

It's also impacting relationships, coming out as the top home-related argument between couples with 67 per cent of the vote. Not doing the dishes came second with 65 per cent, and leaving clothes or shoes on the floor posted third with 62 per cent.

The cost of leaving lights on

Beyond bedtime, 21 per cent of Brits – so roughly 14 million of us – admit to regularly leaving lights on when going to work. The equivalent carbon emissions for this mount up to a staggering 45 flights in one average working day. And we can pin more of the blame on the boys, with men twice as likely (at 31 per cent) to keep their homes lit up while they're at the office than women (14 per cent).

Living in the city can also make a difference, with residents of Newcastle, Manchester, Nottingham, London and Cardiff coming out as the worst culprits.

When you tot up how much we can save by turning lights off when we're not in the room – whether asleep, somewhere else in the home or at work, the savings pile up to a grand £838.66 a year. That's a holiday!

'Lighting can make or break an indoor or outdoor space, and we recognise the importance of well designed, functional lighting,' says Richard Skelton, Brand & E-commerce Director at Utility Design. 'However, this study goes to show that it’s worth being conscious of our energy consumption. Switching off unused lights can have a big impact, from both a money-saving and an environmental point of view.'

'It was interesting to discover that we're most likely to leave the bathroom light on,' Richard adds. 'Perhaps we are slightly too bleary-eyed after our morning showers to make sure that we are being responsible with our energy consumption.'