JUDY WOODRUFF: But, first: Universal health care, free university education, and generous unemployment benefits, are these the keys to happiness? They are all offered in Denmark, the Nordic country Democratic presidential hopeful Bernie Sanders says the United States should look to as a model.

Once again this year, Denmark tops a United Nations poll as the happiest nation on earth. But is this really true?

From Copenhagen, special correspondent Malcolm Brabant investigates.

MALCOLM BRABANT: A happy accident of geography: being born in a country whose safety net offers protection from cradle to grave.

SARAH EGESKOV, Attorney: On a day like this, it's obvious we are gathered with our friends and family to celebrate this little baby, so it's a wonderful day. And in the bigger picture, we live in a great society with a health care system and free education.

MALCOLM BRABANT: Christening their daughter Kaya (ph), attorney Sarah Egeskov and her partner, Claes, hope their state of bliss will leap a generation.

CLAES RASMUSSEN, Financial Adviser: We try to give her some of the same values that we have today and hope for her that she will have the same freedom of speech and freedom of beliefs.

SARAH EGESKOV: And a safe childhood.

CLAES RASMUSSEN: Yes.

SARAH EGESKOV: I don't think we thought about anything evil or threatening through our childhoods, and I hope we can give the same to our daughters.

MALCOLM BRABANT: Pastor Pernille Oestrem's church is in Copenhagen's most racially diverse district. She worries that some of her immigrant parishioners do not enjoy the same level of happiness as ethnic Danes, and she regards it as her mission to try to spread the joy.

PERNILLE OESTREM, Pastor, St. Stefan Church: We don't have any wars and the crime is low. And we can let our children walk to school in the morning by themselves when they're quite young. We don't have to drive them because of drive-by shootings or something like that. That means a lot, that we think we're going to be 90 and have great-great-great-grandchildren.

MALCOLM BRABANT: Danes pay more income tax than any other nationality, earn over $55,000, and the tax rate hits more than 60 percent, but, according to happiness expert Meik Wiking, Danes don't mind.

MEIK WIKING, CEO, The Happiness Research Institute: Just take free access to health care, free access to university education, quite generous benefits if you lose your job. Just those three things mean that a lot of people around the world, if they don't have access to them, will experience unhappiness. And since the welfare state takes care of that, we increase the bottom.

MALCOLM BRABANT: What about the high levels of taxes that people have to pay?

MEIK WIKING: Well it's true, it's really high levels. But I think what's more interesting is that the really high level of support for the for high taxes. If you ask Danes, are you happily paying your taxes, nine out of 10 will say yes.

MALCOLM BRABANT: It's just after 2:00 in the afternoon and some of Copenhagen's bicycling commuters are already heading home. The average Dane only works a 35-hour week, and enjoys five weeks annual paid leave, on top of public holidays, not to mention generous maternity and paternity leave.

According to yet another survey, it has the best work-life balance in the developed world, which is a source of pride for union leader Nana Hojlund.

NANA HOJLUND, VP, Danish Confederation of Trade Unions: Work-life balance means a lot to the Danish people when it comes to happiness, because it's a way that you can both have a really good job, and you can spend hours on your job, and you can also have a family.

MALCOLM BRABANT: Not everyone swallows the concept of perfect little Denmark. British author Michael Booth has lived here for 15 years, and his book debunking the Scandinavian myths is a bestseller.

MICHAEL BOOTH, Author, The Almost Nearly Perfect People: I know the institutes and the researchers like to use that word because it grabs headlines around the world. I don't think the Danes are happy. I think they're more satisfied. They're a pretty somber, dour people. They complain quite a lot.

But when you ask them, are you happy, what they really mean is, well, we're content. Things function here. It's safe. We have a safety net. We don't worry that much. And the difference between the rich and the poor means that you don't have this kind of society of envy that you might have elsewhere in the world.

MALCOLM BRABANT: According to the United Nations, Burundi is the unhappiest country on the planet, followed closely by Syria. The United States is in 13th in the happiness league, just behind Israel and Austria.

Now, according to Bernie Sanders, the U.S. would be a much better place if it emulated cycle-crazy Denmark. But the center-right Danish prime minister has rejected suggestions that this is some sort of socialist utopia, but he's happy that Denmark's welfare system is being looked at as something to aim for.

According to Danish experts, Scandinavians have a genetic predisposition towards happiness. Americans with Scandinavian heritage share those particular traits. Could the Danish model be transported across the Atlantic if the U.S. chose to change the guard?

MEIK WIKING: The same things that drive happiness in Scandinavia are the same things that drive happiness in the U.S. So I think there are some things we could export.

MALCOLM BRABANT: So what would you have to export?

MEIK WIKING: I think what I would do would be to focus on the bottom half of the population to increase the bottom by installing a welfare system inspired by the Nordic countries.

MALCOLM BRABANT: One uniquely Scandinavian social phenomenon that would be difficult to export is what's called the Jantelov, an unwritten code of conformity that decries displays of ostentation or wealth and people who try to rise above their allotted station in life.

MICHAEL BOOTH: How does that sit with Americans and the American dream? Not so well. There's no simple template that could be imposed on America. It doesn't take much to make a happy Dane. Light a fire, light some candles, open a bottle of red wine, and you have got a happy Dane.

I think Americans are a little more demanding when it comes to their happiness. It's enshrined, you know, in the Constitution. They're entitled to it. But they have much bigger ideas of what constitutes happiness. So, can you take it? Will Americans pay 56 percent income tax? I doubt it.

MALCOLM BRABANT: Pastor Pernille Oestrem believes a lack of realism enables the Danes to be so upbeat. But she is acutely aware that, along with the rest of Europe, Denmark is a potential target for Islamic State. So how does she manage to maintain happiness in a time of terror?

PERNILLE OESTREM: Maybe the children that I baptize during this time are actually inheriting a society that looks a lot like the society when I was young. There was a nuclear scare. I didn't know if tomorrow was going to come, but we still went out to play and had our fights and got home to have dinner.

MALCOLM BRABANT: So, there's the perfect advice. Keep calm and carry on. It's just easier if you're Danish. It's in their genes.

For the "PBS NewsHour," I'm Malcolm Brabant in Copenhagen.