The next time the urge to light up a fag strikes after quitting smoking, think of a holiday in the snow-capped mountains -- it may help you beat the craving. A study by a team of researchers in the United States has revealed that happy thoughts dampen the cravings towards addictive substances by curbing the excitement levels in the brain's reward centres.

"If drug addicts, gambling addicts or alcoholics are worse at ignoring their cravings than others, cognitive control might help them kick their habit," lead researcher Mauricio Delgado said. In fact, the researchers from Rutgers University and New York University have based their findings on an analysis of the brain activity of 15 volunteers as they played a simple game, the New Scientist reported.

The participants were asked to associate blue cards with a real $ 4 payoff, and yellow cards with nothing. To control for potential biases, the team swapped the colour assignments for half the volunteers. Before either a yellow or blue card flashed onto a computer screen, the participants received an instruction to either concentrate on their prize or instead on some calming, natural object -- a blue ocean, for instance.

The US team measured how excited the volunteers were by attaching an electrode to each volunteer's finger as raised excitement changes the electrical behaviour of the skin. When there was not $ 4 up for grabs, the participants stayed perfectly calm no matter what they were thinking. But with the flash of a blue card and money on the line, those who thought about the cash showed more excitement than those who pictured the sea or some other succour. The same trend held for the volunteers told to link yellow cards to cash, the researchers found.