When University of Maryland sociologists John Robinson and Steve Martin analyzed more than 35 years of diaries that showed how thousands of people spent their free time, they found only one major difference between people who considered themselves very happy and people who said they were unhappy.

No, it's not what you think. Happy people had sex just a little more often than unhappy people. But unhappy people, it turns out, spend 20 percent more time watching television. Happy people go to church more often, socialize with friends and relatives more, and read newspapers more frequently, but surprisingly, they spend about the same amount of time at work or surfing the internet.

When asked to rank daily activities on a scale of 0 to 10, sex, at 9.3, did lead the list, followed closely by playing sports, at 9.2. Next came caring for, playing with or reading to children, followed by church, sleep and socializing. At the bottom? Shopping, at 4.3 and cleaning house at 4.2. Watching television scored a 7.8, just ahead of eating, hobbies and exercise, but slightly behind reading and taking work breaks.

A generation ago, the then-king of Bhutan said that he was not overly concerned with his country's weak economic growth because what really matters is "gross national happiness" and his subjects were happy. Ever since, different systems have been created to measure gross national happiness and to rank nations.

In 2006, a British psychologist, Adrian White, used such an index to create a "world map of happiness." It ranked 178 nations, from Denmark, the world's happiest country, to impoverished, war-torn Burundi, the unhappiest. The following year, the international Organization for Economic Cooperation and Development published a list of the 18 nations whose populace watched the most TV.

Compare that list to White's global happiness index, and lo and behold - the happiest nations, led by Denmark, watched the least TV. Switzerland, the second happiest nation, ranked just behind Denmark in average weekly viewing hours.

Americans led the world in hours glued to the screen but, presumably because of the United States' wealth, placed 23rd on the happiness index. The No. 2 TV-watching country, Turkey, came in at an unhappy 131.

Do such findings mean that watching television makes you unhappy? Researchers don't know. If the ease and low cost of television-watching mean people squander time they would otherwise pass in more pleasurable activities such as socializing with friends, the answer is yes. But it's also likely, Robinson says, that television is a refuge for people who, for a variety of reasons, are less social beings anyway or are already unhappy. For them, TV is a refuge.

Our guess is that both things are true. Television offers scores of channels displayed on desk-size screens, and though the programming is nothing to rave about, you can watch it while looking like a slob and without braving the cold. And TVs, at least not yet, don't talk back or demand anything more than payment of the monthly bill.

Since entire countries appear to show that happiness equals less TV time, it's clear that more research is called for. But just in case, it wouldn't hurt to turn off the tube tonight and talk to some fellow human beings.