By Denise Foley
From Completely You

We're not using a lot of smiley faces on Twitter these days. That's the finding of a team of scientists from The University of Vermont who developed a graph that illustrates a gradual downward swing in mood over the past three years. To create it, they assessed more than 46 billion words in tweets by 63 million Twitter users around the world.

The graph itself looks something like a frown.

The researchers don't speculate why Twitter users aren't happier. They saw clear drops in happy words during swine flu epidemics, the tsunami in Japan, the U.S. economic bailout, and even the deaths of actor Patrick Swayze and, surprisingly, Osama Bin Laden.

They found that Tweeters, who tend to be young, are happiest on the weekend, with Monday and Tuesday being the most down days. And, if tweets are to be trusted, people really love Christmas. In fact, it's the happiest day of the year.

But the researchers weren't really trying to determine why people were or weren't happy. Their motive: "In measuring happiness, we construct a tunable, real-time, remote-sensing and noninvasive text-based hedonometer." In other words, a happiness sensor that policymakers could use to assess the mood of the country, or that a sales rep could access to determine the happiness quotient of the city where he's headed for business.

These days, happiness -- which is one focus of the positive psychology movement -- is such a popular scientific subject that it has its own journal: the Journal of Happiness Studies.

I asked Caroline Miller, a life coach from Virginia who received her master's in applied positive psychology from the University of Pennsylvania (where positive psychology was born), how happiness wound up under the microscope.

"The emerging science of positive psychology is growing precisely because people want to know what is behind authentic emotional flourishing," says Miller, who is also the co-author of Creating Your Best Life: The Ultimate Life List Guide.

Yet, despite our search for it, many of us find happiness to be elusive. That, in part, is because we're looking in all the wrong places, says Miller.

"Too often, we've gotten caught up in thinking that getting that next thing or raise will be our ticket to well-being, and we've been disappointed," she says. "Research shows that college students think fame and money will bring them happiness, but research from the positive psychology world proves otherwise. Making a bucket list and tackling it, investing in friendships and experiences, and living without regrets have been found to be some of the things that, in hindsight, have made life richer and more fulfilling."

For some wise advice on how to be happy, Miller pointed me toward the Legacy Project. This six-year study conducted by Dr. Karl Pillemer, professor of gerontology in medicine at the Weill Cornell Medical College, is based on interviews with more than 1,200 people older than 70 (he calls them "the wisest Americans") in which he asked them all one question: "Over the course of your life, what are the most important lessons you would like to pass on to younger people?"

Listen up, tweeters, this won't fit into 140 characters. Here's what your elders say about upping your happiness quotient:

1.    Pick a career based on your passion for the work, not the size of the paycheck.

2.    Practice good health habits. You're going to be in that body for a long time; make it last.

3.    When opportunity knocks, answer with a resounding "Yes." Take a risk, even a leap of faith.

4.    Get to know someone well before you marry him or her.

5.    Travel more. Most people consider travel adventures to be the high points of their lives.

6.    Express yourself now. Tell the people you love that you love them. Settle arguments and mend grudges right away. You never know how much time you have.

7.    Live by the mantra, "Life is short," because even if you live to be 100, you're going to think it is.

8.    Choose to be happy. Recognize that it is a choice.

9.    Stop worrying. Most of the things you're worried about won't happen.

10.  Enjoy simple pleasures. Take time to smell and drink the coffee, listen to the birds and find the beauty in the world around you.