(CNN) On Saturday, 26 countries stand to be a lot happier -- simply by taking part in an iconic singing competition.
All are competing in the final of Eurovision 2018, also known as the Eurovision Song Contest, a flamboyant international TV competition that has been running since 1956.
Such is the popularity of the contest, held this year in Lisbon, Portugal, that participant countries now come from Israel and Australia. It is broadcast to millions of people in countries that don't compete, such as the United States, Canada, New Zealand and China.
Now, there may be reason for more countries to participate.
A new study suggests that when a nation takes part in Eurovision, it has a 13% chance of higher "life satisfaction" among its population compared with those who don't.
This life satisfaction may in turn benefit their physical and mental health, according Filippos Filippidis, an epidemiologist in public health at Imperial College London, who led the study published Friday in the journal BMC Public Health.
His team found that people were 4% more likely to be satisfied with their life for every increase of 10 places on the final score board -- for example, if their country finished second rather than 12th.
The teams of Latvia reacts as they go to final after the semi-final of the Eurovision Song Contest 2017.
However, doing badly in the contest was also associated with a greater increase in life satisfaction compared with not taking part at all. So, achieving "nul points" -- a zero score -- is not so bad after all.
The research backs up studies showing that hosting or succeeding in sporting fixtures like the US Super Bowl and the football World Cup can boost a city or nation's well-being and productivity.
One US study found that making the playoffs or finals in professional sporting events related to a decline in suicide in 30 US metropolitan areas between 1971 and 1990, while another found increased productivity in the city of the winning Super Bowl team.
Another study of the Olympic Games, the FIFA World Cup and the UEFA European Championship found that the "feel-good" factor associated with hosting football events is large and significant, although an effect on happiness was not found.
Ireland must have been particularly happy in the 1990s, when it won the contest seven times.
Previous high-profile wins include Swedish supergroup ABBA, who took the crown in 1974 with "Waterloo"; Bucks Fizz, who won for the UK with "Making Your Mind Up" in 1981; and Céline Dion, who won in 1988 for Switzerland.
Eurovision Song Contest Winner Celine Dion of Switzerland in 1988.
But David Spiegelhalter, the Winton Professor for the Public Understanding of Risk at Cambridge University, said that although it may be interesting to think of reasons for this association, he would be very skeptical of there being a causal link between the two. He was not involved in the new study.
Filippidis said more research was needed to confirm the association but added that the work showed the importance of considering the unintended consequences of events that reach a wide audience.
His team -- from competing countries Greece, Italy, Ireland, Australia and the UK -- is usually researching the effect of public policies, environmental factors and economic conditions on people's lifestyle and health.
But last year, during the competition, they began discussing whether it could also affect a country's national well-being and decided to investigate.
Swedish pop group Abba, performs during the the Eurovision Song Contest 1974.
They collected data from the Eurobarometer survey , which included answers from over 160,000 people from 33 European countries to a question on life satisfaction taken just after the finals of the contest between 2009 and 2015. They also analyzed each country's performance in the contest, ranking those at 20th place or below as "terrible."
Winning was not associated with improved life satisfaction, but the higher the ranking per 10 places, the higher the odds of being "very satisfied."
The audience watches the screen as they wait for results at the Eurovision Grand Final on May 14, 2017 in Kiev, Ukraine.
The scientists also compared data from countries that participated but did badly with those that didn't take part at all. They found that taking part but finishing near the bottom of the table was associated with a 13% higher chance of life satisfaction compared with not taking part in the competition.
Filippidis said the results surprised him. "I thought there may be something there, but the results were quite consistent across countries.
"If England win the football World Cup, even if you are not interested in football, you will see that other people are happy talking about it and smiling. Being happy is contagious, and it can be the same for misery and bad moods."
Professor Mike Berry, consultant clinical forensic psychologist at Birmingham City University, wasn't involved in the study but described the work as "a really interesting, amusing and well-designed study."
He added that although it did not show causation, the link with greater satisfaction sounded "feasible." However, he said the problem was that the effect was fleeting.
"There was a marked increase in attendance and productivity during the 1966 World Cup soccer finals in England, which England won," he explained. "Workers attended factories every day, so they could talk about the various games."
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Berry was also not surprised that winning was not the important part. "We just had the end of the Championship football last weekend. The teams and their fans avoiding last-minute relegation were often happier than the team that actually was promoted."
In the UK, he said, the next event hat may impact the nation's satisfaction was next week's marriage of Prince Harry to Meghan Markle.
"For a few days, there will be a major increase in public mood, but more worrying the number of babies born nine months later and being named Harry or Meghan."
Image copyright AFP Image caption Portugal's Salvador Sobral looked decidedly cheerful after his song won last year
Eurovision may have a reputation for being up-tempo and sprinkled with sequins, but the secret to a winning song may actually be its gloom factor.
We've unpicked the sound waves of every song entered since 2006 to try to answer this burning question: Is there a recipe for a winning Eurovision song?
Unexpectedly, perhaps, melancholia sells: in eight of the last 12 contests, winners have been sadder than the average song.
And yes, in case you're wondering, last year's winner Salvador Sobral's Amar Pelos Dois is the saddest-sounding winning song - although you probably didn't need data to tell you that.
Eurovision songs have been consistently getting more melancholy, and this year's entries are a full 30% sadder than in 2006.
Guess they got the memo about sadness winning votes.
But hey, if you feel firmly that Eurovision should just be about cheery tunes all hope isn't lost.
Some winners have stuck to a happy sound and still gone home with the big prize, most notably Lena with Satellite in 2010, and Lordi's Hard Rock Hallelujah in 2006.
We've worked out if a song sounds happy or not by using a measure of musical positivity called valence, used by streaming sites to auto-recommend new music.
Where are the happy songs?
Valence is based on songs' key, harmony and beats - and ignores the lyrics altogether.
"It's all from the waveform," said Eliot Van Buskirk, data storyteller at Spotify.
"The song Happy by Pharrell Williams has an incredible high valence rating, as one would expect, even though the valence attribute has no idea that the song is literally called Happy."
There's a clear Eurovision gloom belt cutting across central and eastern Europe, but things perk up significantly if you look further east and to Scandinavia.
Azerbaijan, Slovenia and Slovakia have entered the saddest songs.
Andorra's entries are the happiest of all - but then the country has only participated four times in the time period. Turkey and Ukraine can also be relied upon to enter consistently cheerful songs, although Turkey hasn't participated since 2012.
The UK normally submits songs on the sadder end of the scale, but the happiest song of all also comes from the UK.
Andy Abraham holds the record for perkiest song, with Even If from 2008.
But cheerful tunes couldn't help Andy win the judges over: the song ended last.
Key
The most common Eurovision key is C major. A whole 30 of the 456 entries we analysed opted for it.
But for a winning song, you may be better off choosing D minor - the "saddest of all keys" if Spinal Tap is to be believed.
Three of the last 12 winners have opted for it: Molitva (2007), Fairytale (2009) and Rise Like a Phoenix (2014).
Eurovision winners are twice as likely to be in a minor key. Eight of the last 12 winners have been in a minor key.
Image caption Conchita Wurst's Rise Like a Phoenix is just one of three winning songs in D minor
Also, a key change is not nearly as effective a winning tactic as you might think, so cross it off your Eurovision drinking game now.
Once as quintessential a part of a Eurovision show as wind machines and costume changes, climactic finishes in a higher key may be on the way out.
Winning songs are less likely than other entries to contain a key change. And song writers are catching on: key changes have become increasingly less common over the last decade.
Tempo
What about speed?
Winners are all over the place on this one: from Molitva's stately 77bpm to Running Scared's 172bpm.
Andorra averages the highest tempo by far at 177bpm, whereas Montenegro's entries hover around a more leisurely 100bpm.
There may not be a clear beat that will lead you to Eurovision fame - but there does seem to be a speed that kills. Four entries in the last decade have used 128bpm and come last or second-to-last.
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Image copyright Andres Putting Image caption Russia's Julia Samoylova performing I Won't Break
Russia has suffered a shock elimination from Eurovision in Thursday's second semi-final.
It will be the first time the country has not qualified since 1998, going back to before the semi-final stage of the competition was introduced.
Australia, Denmark and Hungary are among the countries to have gone through to Saturday's grand final.
The event was held in Lisbon and also saw Norway's Alexander Rybak - who won the competition in 2009 - qualify.
One country which won't see Saturday's final is China, after the European Broadcasting Union (EBU) barred one of the country's most popular TV channels from broadcasting it after Mango TV censored LGBT elements of the first semi-final on Tuesday.
Image copyright PA Image caption Alexander Rybak is going for glory a second time round
Russia's act, Julia Samoylova, was supposed to take part in 2017 but was unable to do so after Russia did not participate, when the event was held in Ukraine. She appeared instead this year, but was unable to progress beyond the semi-final.
Image copyright EPA
No mercy for Russian singer in Ukraine after Eurovision flop by BBC Monitoring
Ukrainians have been gloating on social media after Russia's elimination in the second semi-final.
The target of the mockery was Julia Samoylova, who could not take part in the contest in Kiev in 2017 because of a visit she had made to annexed Crimea.
Anti-Kremlin blogger Oleh Leusenko published several pictures "in memory" of Samoylova, one of which contained the text: "Russia wasn't at the Olympics. Russia wasn't at the Paralympics. Russia will not be at Eurovision. We will see a day when Russia will be nowhere."
Russia's failure to qualify was also widely discussed by Russians on Twitter, with many users criticising Samoylova's vocal abilities.
Few users who spoke in her defence took shots at the contest itself, with one saying: "We should have abandoned this abominable circus long ago."
Meanwhile, Ukraine's contestant made it to the final, which prompted even more joy in Ukraine.
Image copyright EPA
Poland was also eliminated - despite their song Light Me Up being well-liked and well-received in Lisbon's Altice Arena.
The UK automatically qualifies for Saturday's grand final.
Underdogs Slovenia were also among those selected to compete in the final, where singer Lea Sirk will be hoping to better her country's 2001 placing of seventh.
The pop star helping Cyprus become Eurovision favourite
First 10 Eurovision finalists chosen
What these UK Eurovision acts know now
Rybak opened the proceedings to raptures from the stadium - clearly still enjoying a large fan base following his Fairytale win nine years ago.
Another favourite of the night, Rasmussen, came not long after with their rousing Viking anthem, which saw the crowd singing along followed by a huge send-off at the end.
Image copyright PA Image caption We got sequins and we got love - Australia's Jess Mauboy
But the best reception of the night went to Australia's Jessica Mauboy, who gave an impassioned performance of her song We Got Love. The audience almost took the roof off for the Darwin singer, who looked truly overwhelmed by the response, after she finished.
It seems that the performance carried over to the audience at home as well, with Twitter users commenting on Jessica's energy and "presence".
Other notable acts to go through from the second semi-final include metal act AWS from Hungary and Sweden's Benjamin Ingrosso - cousin of Swedish House Mafia's Sebastian Ingrosso.
There were 18 countries taking part in the second semi-final, with eight being eliminated. The 10 that qualified will join the first 10 countries put through from Tuesday's first leg.
Image copyright Andres Putting Image caption Sweden's Benjamin Ingrosso will take part in the final
The second semi-final saw the following countries selected through a combination of jury and public vote: Norway, Serbia, Denmark, Moldova, The Netherlands, Australia, Hungary, Sweden, Slovenia and Ukraine
In addition, the Big Five - France, Germany, Italy, Spain and the UK, plus host country Portugal - get put through automatically. This is on account of these countries making the largest financial contribution to the event.
Those who did not go through are Romania, San Marino, Russia, Georgia, Poland, Malta, Latvia and Montenegro.
Media playback is unsupported on your device Media caption Netta Barzilai, whose song TOY has racked up millions of views on YouTube, is representing Israel in the Eurovision Song Contest
The successful countries join the likes of bookies' favourite Cyprus - represented by pop star Eleni Foureira - and Israel's Netta in the final.
Israel and Norway are now neck and neck as the second favourites to win the competition.
The UK's entrant, SuRie, has the weight of British hopes resting on her shoulders. The 29-year-old will perform her anthemic track, Storm, which she says is intended to inspire hope.
Image copyright EPA Image caption Will SuRie weather the Storm in Saturday's final?
The 26 countries to make it through to Saturday's final are:
Albania
Austria
Australia
Bulgaria
Cyprus
Czech Republic
Denmark
Estonia
Finland
France
Germany
Hungary
Ireland
Israel
Italy
Lithuania
Moldova
The Netherlands
Norway
Portugal
Serbia
Slovenia
Spain
Sweden
Ukraine
United Kingdom
You can watch the Eurovision Song Contest grand final on Saturday 12 May on BBC One from 20:00 (BST).
Image copyright EPA
Follow us on Facebook, on Twitter @BBCNewsEnts, or on Instagram at bbcnewsents. If you have a story suggestion email entertainment.news@bbc.co.uk.
Image copyright Andres Putting Image caption Russia's Julia Samoylova performing I Won't Break
Russia has suffered a shock elimination from Eurovision in Thursday's second semi-final.
It will be the first time the country has not qualified since 1998, going back to before the semi-final stage of the competition was introduced.
Australia, Denmark and Hungary are among the countries to have gone through to Saturday's grand final.
The event was held in Lisbon and also saw Norway's Alexander Rybak - who won the competition in 2009 - qualify.
One country which won't see Saturday's final is China, after the European Broadcasting Union (EBU) barred one of the country's most popular TV channels from broadcasting it after Mango TV censored LGBT elements of the first semi-final on Tuesday.
Image copyright PA Image caption Alexander Rybak is going for glory a second time round
Russia's act, Julia Samoylova, was supposed to take part in 2017 but was unable to do so after Russia did not participate, when the event was held in Ukraine. She appeared instead this year, but was unable to progress beyond the semi-final.
Image copyright EPA
No mercy for Russian singer in Ukraine after Eurovision flop by BBC Monitoring
Ukrainians have been gloating on social media after Russia's elimination in the second semi-final.
The target of the mockery was Julia Samoylova, who could not take part in the contest in Kiev in 2017 because of a visit she had made to annexed Crimea.
Anti-Kremlin blogger Oleh Leusenko published several pictures "in memory" of Samoylova, one of which contained the text: "Russia wasn't at the Olympics. Russia wasn't at the Paralympics. Russia will not be at Eurovision. We will see a day when Russia will be nowhere."
Russia's failure to qualify was also widely discussed by Russians on Twitter, with many users criticising Samoylova's vocal abilities.
Few users who spoke in her defence took shots at the contest itself, with one saying: "We should have abandoned this abominable circus long ago."
Meanwhile, Ukraine's contestant made it to the final, which prompted even more joy in Ukraine.
Image copyright EPA
Poland was also eliminated - despite their song Light Me Up being well-liked and well-received in Lisbon's Altice Arena.
The UK automatically qualifies for Saturday's grand final.
Underdogs Slovenia were also among those selected to compete in the final, where singer Lea Sirk will be hoping to better her country's 2001 placing of seventh.
The pop star helping Cyprus become Eurovision favourite
First 10 Eurovision finalists chosen
What these UK Eurovision acts know now
Rybak opened the proceedings to raptures from the stadium - clearly still enjoying a large fan base following his Fairytale win nine years ago.
Another favourite of the night, Rasmussen, came not long after with their rousing Viking anthem, which saw the crowd singing along followed by a huge send-off at the end.
Image copyright PA Image caption We got sequins and we got love - Australia's Jess Mauboy
But the best reception of the night went to Australia's Jessica Mauboy, who gave an impassioned performance of her song We Got Love. The audience almost took the roof off for the Darwin singer, who looked truly overwhelmed by the response, after she finished.
It seems that the performance carried over to the audience at home as well, with Twitter users commenting on Jessica's energy and "presence".
Other notable acts to go through from the second semi-final include metal act AWS from Hungary and Sweden's Benjamin Ingrosso - cousin of Swedish House Mafia's Sebastian Ingrosso.
There were 18 countries taking part in the second semi-final, with eight being eliminated. The 10 that qualified will join the first 10 countries put through from Tuesday's first leg.
Image copyright Andres Putting Image caption Sweden's Benjamin Ingrosso will take part in the final
The second semi-final saw the following countries selected through a combination of jury and public vote: Norway, Serbia, Denmark, Moldova, The Netherlands, Australia, Hungary, Sweden, Slovenia and Ukraine
In addition, the Big Five - France, Germany, Italy, Spain and the UK, plus host country Portugal - get put through automatically. This is on account of these countries making the largest financial contribution to the event.
Those who did not go through are Romania, San Marino, Russia, Georgia, Poland, Malta, Latvia and Montenegro.
Media playback is unsupported on your device Media caption Netta Barzilai, whose song TOY has racked up millions of views on YouTube, is representing Israel in the Eurovision Song Contest
The successful countries join the likes of bookies' favourite Cyprus - represented by pop star Eleni Foureira - and Israel's Netta in the final.
Israel and Norway are now neck and neck as the second favourites to win the competition.
The UK's entrant, SuRie, has the weight of British hopes resting on her shoulders. The 29-year-old will perform her anthemic track, Storm, which she says is intended to inspire hope.
Image copyright EPA Image caption Will SuRie weather the Storm in Saturday's final?
The 26 countries to make it through to Saturday's final are:
Albania
Austria
Australia
Bulgaria
Cyprus
Czech Republic
Denmark
Estonia
Finland
France
Germany
Hungary
Ireland
Israel
Italy
Lithuania
Moldova
The Netherlands
Norway
Portugal
Serbia
Slovenia
Spain
Sweden
Ukraine
United Kingdom
You can watch the Eurovision Song Contest grand final on Saturday 12 May on BBC One from 20:00 (BST).
Image copyright EPA
Follow us on Facebook, on Twitter @BBCNewsEnts, or on Instagram at bbcnewsents. If you have a story suggestion email entertainment.news@bbc.co.uk.
