The UN's Sustainable Development Solutions Network released its 2016 World Happiness Report on Wednesday, the group's fourth annual survey seeking to quantify happiness.
Sweden has consistently ended up high in this kind of lists for decades, thanks to relatively strong social support, affluence and comparatively honest and accountable governments.
But the new rankings deemed that the Danes are the world's happiest, closely followed by Switzerland and Sweden's other Nordic neighbours Iceland, Norway and Finland.
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Sweden meanwhile found itself beaten by another four countries, just managing to clinch a spot in the top-10. It dropped from eighth in last year's ranking and fifth two years earlier.
However, John Helliwell, one of the editors of the report, said it was too early to say whether or not the Swedes are getting unhappier, noting that all the best-performing countries were the same as last year, although their order had shifted slightly.
"All of the top-10 countries are very close, so that small changes in the levels can cause rankings to change. Sweden's three-year score went down from 7.36 to 7.29. The New Zealand and Australian scores both went up by about the same amount. The result was that they are now above Sweden."
"It will take a longer run of data to see if there is something larger going on. For the moment, the ranking change is not really significant, more like repeat winning games between equally matched teams," the University of British Columbia professor told The Local.
The report looked at data recording how highly people evaluate their lives on a scale running from 0 to 10. The rankings, which are based on surveys in 157 countries, revealed a world average score of 5.1.
READ ALSO: Why Malmö is Sweden's happiest city
The happiest countries in the world
7) The Netherlands
8) New Zealand
The least happy countries in the world