Finland remains the happiest country in the world for the ninth year in a row, followed by Iceland, Denmark. Costa Rica ranked fourth, the highest position ever recorded for a Central American country. Afghanistan again came last, with Sierra Leone and Malawi completing the bottom three.

The researchers say a clear trend is visible in western Europe and North America, where young people report lower levels of happiness than older generations. In countries including the United States, Canada, Australia and New Zealand, younger respondents now rank among the least happy worldwide.

The report links part of the decline to the growing use of social media. Oxford professor Jan-Emmanuel De Neve, one of the authors, said the effect depends on how people use it.

“The global evidence makes clear that the links between social media use and our well-being heavily depend on what platforms we’re using, who’s using them and how, as well as for how long,” he said.

“Heavy usage is associated with much lower well-being, but those deliberately off social media also appear to be missing out on some positive effects. Beyond the complexity, it is clear that we should look as much as possible to put the ‘social’ back into social media.’ 

There has been talk in the Netherlands about restricting social media use to the over-15s, and a clear majority of the population are in favour of such a plan. Among people aged 16 to 28, 60% back restrictions.

The World Happiness Report has been published annually since 2012 and is based on surveys in 136 countries. People are asked to rate their lives on a scale from 0 to 10, and the results are averaged over three years to produce the ranking.

Researchers then analyse factors such as income, life expectancy, freedom and social support to explain differences between countries.