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Happiness is infectious, US researchers claim

9 December 2008

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Happiness really does rub off — a person’s happiness depends on the happiness of others with whom they are connected, according to research published on the British Medical Journal website.

The study finds that happiness is not just an individual experience or choice, but is dependent on the happiness of others to whom individuals are connected directly and indirectly, and requires close proximity to spread.

For example, the authors claim that a friend who becomes happy and lives within a mile increases your likelihood of happiness by 25%.

Professor Nicholas Christakis from Harvard Medical School and Professor James Fowler from the University of California, San Diego, analysed data collected from 5,124 adults aged between 21 and 70, who were recruited and followed between 1971 and 2003.

The researchers measured how social networks were correlated with reported happiness. They found that live-in partners who become happy increase the likelihood of their partner being happy by 8%. Similar effects were seen for siblings who live close by (14%) and neighbours (34%). The study found that people who are surrounded by happy people are likely to become happy in the future.

However, work colleagues did not affect happiness levels, suggesting that social context may curtail the spread of emotional states.

The authors say: “Changes in individual happiness can ripple through social networks and generate large scale structure in the network, giving rise to clusters of happy and unhappy individuals.”

They conclude: “Most important from our perspective is the recognition that people are embedded in social networks and that the health and wellbeing of one person affects the health and wellbeing of others. This fundamental fact of existence provides a fundamental conceptual justification for the specialty of public health. Human happiness is not merely the province of isolated individuals.”