Happiness is a social phenomenon

Nicholas Christakis from Harvard University says :

"Clusters of happy and unhappy people are visible
in the network, and the relationship between people’s
happiness extends up to three degrees of separation (for
example, to the friends of one’s friends’ friends). People
whoare surrounded by many happy people and thosewho
are central in the network are more likely to become happy
in the future. Longitudinal statistical models suggest that
clusters of happiness result from the spread of happiness
and not just a tendency for people to associate with
similar individuals. A friend who lives within a mile (about
1.6 km)andwhobecomeshappy increases the probability
that a person is happy by 25% (95% confidence interval
1% to 57%). Similar effects are seen in coresident
spouses (8%, 0.2% to 16%), siblings who live within a
mile (14%, 1% to 28%), and next door neighbours (34%,
7% to 70%). Effects are not seen between coworkers. The
effect decays with time and with geographical separation.
Conclusions People’s happiness depends on the
happiness of others with whom they are connected. This
provides further justification for seeing happiness, like
health, as a collective phenomenon."

read here the whole paper