A new study from the U.K. confirms the conventional wisdom: friends and exercise make us happy. But it also shows how unhappy people drag us down.
The idea that unhappiness leads to bad consequences is not a new one. But several recent studies have added a bit of nuance to the long-standing general beliefs of "Think Well, Be Well" and the impact of positive thinking on a person's recovery and health.
In the longitudinal, 70-year "Grant Study" of Harvard undergraduates that formed the basis of the June 2009 "What Makes Us Happy" cover story in The Atlantic, researcher George Valliant found a clear link between depression and health problems. Of the men in the study who reported signs of depression at age 50, 70 percent had died or were chronically ill by age 65.
But correlation is not the same thing as causation. Did the depression cause the illness or early death? Or did the two simply go hand in hand? Both Valliant and the authors of a new book, The Longevity Project, came to the same conclusion: sadness does not make you sick any more than happiness makes you well.
The Longevity Project is based on the results of a longitudinal study instigated by psychologist Lewis Terman (and therefore known as the "Terman Study"). The Terman study followed a group of 1,500 Californians over eight decades, starting in 1921. All of the children selected for the Terman study were judged to be of high IQ and, therefore--at least in theory--people who had high potential for living long, happy, successful, and productive lives. The Grant Study participants, all of whom were students at Harvard, were considered to have the same potential.
Although Valliant focused on what factors led to a happy and productive life, and Howard S. Friedman and Leslie R. Martin, the authors of The Longevity Project, looked primarily at what factors led to a long life, both investigative teams found that being bright didn't guarantee anything. They also came to the same conclusions about health and happiness: namely, that there were certain lifestyle patterns that seemed to lead to both happiness and health, just as there were other lifestyle paths and patterns that seemed to lead to both sadness and sickness. But being sad and being sick were both separate, resultant outcomes of those lifestyles, rather than a cause-and-effect pair.
All three researchers concluded that one of the biggest factors in both a happy life and a long life was having strong and healthy social connections. Beyond that, the people who tended to have "happy-well" outcomes were conscientious, emotionally healthy individuals who set and actively pursued goals; who incorporated strong social networks, exercise and "healthy" eating/drinking habits organically into their everyday lives; who were optimistic but not to the point of being careless or reckless; social enough to form strong networks, but not so social as to pursue unhealthy habits for peer approval; and who felt engaged and satisfied in their careers, marriages, and friendships.
According to Friedman and Martin, however, there's one area where unhappiness does seem to play a causal role. It may not directly sicken or shorten the life of the person experiencing the unhappiness. But it apparently can be toxic for people who have to live with that unhappy person. Unlike the Grant Study, which interviewed only the Harvard men, the Terman study also interviewed the spouses of the people in the study, to gauge their impact on study participants' lives. And in the Terman study, women married to unhappy men tended to be unhealthier, and live shorter lives, than women married to happy men. Oddly, the reverse was not true. The happiness of the woman had very little effect on the lifespan or happiness of her husband.
The explanation Friedman and Martin came up with for this initially puzzling result was that--especially for the Terman subjects, who were all born around 1910--a man married to an unhappy wife could get away from her influence through work and outside activities. But a woman in that era, married to an unhappy man, was more likely to be trapped in a world poisoned by that unhappiness.
Those results are echoed in the "first-wave" findings of a new longitudinal study just getting underway in Britain. In 2009, the U.K.'s state-funded Economic and Social Research Council commissioned a longitudinal research study called "Understanding Society" to follow 100,000 people in 40,000 households over the next few decades to try to determine what factors lead to improved family lives.
The first-wave (e.g. first-year) findings of that study have just been published. And one of the data points the study reported was that the happiness of children in a household (aged 10 to 21, living at home) is significantly affected by the happiness of their mother--or, at least her happiness in terms of her marriage. Only 55 percent of children whose mothers reported that they were unhappy in their marriages said they were completely happy at home, versus 73 percent of those whose mothers reported being very happy in their marriages. The happiness of the fathers was less significant.
There are a lot of caveats that need to be applied to the U.K. study, of course. First, the results represent a single, self-reported data point, not a long view over time. So it's a bit early to give too much weight to the British results. The Grant and Terman studies also included quantifiable health and death data as well as the interviewer's interpretation of each individual's responses as a check to people's self-reports. What's more, the U.K. study report didn't note what percentage of the study group's mothers worked or stayed at home all day, or who did the primary caregiving for the children involved, so the data is lacking a bit of context.
Generally speaking, however, women still tend to spend more time with children than their husbands do, and provide a greater share of the childcare. And if Friedman and Martin's conclusion is correct, that unhappiness poisons those who are, for whatever reason, trapped in its company and under its influence ... then the Understanding Society results make sense.
The Understanding Society study is only in its first year, of course, and it's not clear how much detail will be collected from each subject over time, given that the study size is so large. In any event, it will be years before the researchers can determine the long-term impact of the parents' unhappiness is on the children in the study.
But the Terman study and the first-wave survey results of the Understanding Society study both make it clear that while unhappiness itself may not what makes unhappy people sick, it might very well be toxic to the people around them. And that's regardless of what other healthy personality, lifestyle habits, or other factors those people may have going for them. Unhappiness, in other words, may be a bit like second-hand smoke. And while it may not be quite as directly lethal, it's a whole lot harder to regulate.