Finland ranked as the world's happiest country for the eighth straight year in the World Happiness Report, with locals and experts thanking its grand lakes and strong welfare system for boosting its mood.

Afghanistan, plagued by a humanitarian catastrophe since the Taliban regained control in 2020, once again ranked as the unhappiest country in the world.

The United States fell to 24th place, its lowest score since the report was first published in 2012, when it recorded its highest showing at number 11.

"The number of people dining alone in the United States has increased 53 percent over the past two decades," the authors said, noting that sharing meals "is strongly linked with well-being".

In 2023, roughly one in four Americans reported eating all their meals alone the previous day, the report said.

"The increasing number of people who eat alone is one reason for declining well-being in the United States," it said.

It also noted that the United States was one of few countries to see a rise of so-called "deaths of despair" -- from suicide or substance abuse -- at a time when those deaths are declining in a majority of countries.

The report surveyed people worldwide in 2022-2024, before US President Donald Trump's shakeup of national and global affairs since returning to the White House in January.

Nordic countries all stayed among the 10 happiest, with Denmark, Iceland and Sweden trailing Finland, which slightly extended its lead over runner-up Denmark.

Meanwhile, Costa Rica and Mexico entered the top 10 for the first time, at the sixth and 10th spot respectively.

The happiness ranking is based on a three-year average of individuals' self-assessed evaluations of life satisfaction, as well as GDP per capita, social support, healthy life expectancy, freedom, generosity and corruption.

Finns 'relatively satisfied' 

"It seems that Finnish people are relatively satisfied with their lives," Frank Martela, an assistant professor specialised in well-being and happiness research at Aalto University, told AFP.

It could largely be explained by Finns living in "quite a well-functioning society", he said.

"Democracy is functioning well, we have free elections, free speech, low levels of corruption and all of these have shown to predict higher levels of national well-being," Martela said.

He added that the Nordic countries also all have relatively strong welfare systems -- with parental leave, unemployment benefits and mostly universal healthcare -- which also contribute to higher levels of well-being on average.

Eveliina Ylitolonen, a 23-year-old student in Helsinki, said she believed that Finns' focus on enjoying beautiful nature could help explain the consistently high level of happiness in the Nordic country, known for its deep forests and over 160,000 lakes.

"Nature is an important part of this happiness," Ylitolonen told AFP.

Jamie Sarja-Lambert, a professional video gamer who moved to Finland from the United Kingdom, agreed.

"Seems like everyone is a lot more in touch with nature, going outside and socialising, more of a community," he told AFP.

This year, the authors of the happiness report said new evidence indicates that engaging in acts of generosity and believing in the kindness of others are "significant predictors of happiness, even more so than earning a higher salary".

They also noted that in general "people are too pessimistic about the kindness of their communities", and that "the return rate of lost wallets is much higher than people expect".

Nordic countries also "rank among the top places for expected and actual return of lost wallets".