The Happiness Thermostat: Is it Adjustable?

Many things bring momentary pleasure, but it’s hard to assess what factors yield long-term happiness without doing a long term study. Well, the results of a very long-term study are finally in (published in PNASProceedings of the National Academy of Sciences), and these results have the potential to overturn a long-standing happiness theory in psychology.

A pretty widely accepted theory in psychology says that one’s long-term happiness level is primarily dictated by genetics and inherent personality traits. This theory, called set-point theory, posits that although major life events can temporarily bring you down (or up), everyone has a set-point happiness level that they eventually return to over time (within a couple of years). It’s kind of like a thermostat: if the temperature in the room is set to 72 ºF, the room may cool down temporarily if you throw open all the windows, but it will eventually equilibrate back to 72.

If you’re usually a happy person, set-point theory seems like a good thing (“I’m sad because I lost my job, but I’ll eventually get back to my normal happy self”). Conversely, if you’re an Eeyore, set-point theory makes the rather dismal prediction that you’re never going to really get any happier.

Interestingly, set-point theory creates something of a paradox for economists. Economists operate under the assumption that people make economic choices (e.g., making purchases, saving money, switching jobs) in an attempt to improve their long-term happiness level. But if set-point theory is true, then nothing really has a substantial long-term effect on happiness, and economists’ predictive models for consumer behavior shouldn’t work.

Fortunately for economists and Eeyores alike, the research published last week indicates that people’s long-term happiness levels can and do change. This research is based on a long-running survey of ~60,000 people (in Germany), tracking their self-reported life satisfaction among other things, over the course of ~25 years. The researchers averaged reported life satisfaction over chunks of 5 years at a time – to even out minor fluctuations – and looked at how those 5-year-averages compared. If set-point theory was the whole picture, then the happiest people in the first five years should be the happiest people in the last five years – but this wasn’t the case. Almost 40% of the people surveyed became quite a bit happier or less happy, compared to everyone else, over the course of the 25 years (they moved up or down 25 or more percentile points).

Since basic personality traits are believed to be nearly set in stone by adulthood, changes in external circumstances and life choices should be the cause of these drifts in long-term happiness. The researchers examined data about people’s preferences and life choices to see what factors were associated with higher long-term happiness. Some of the main factors that stood out are depicted in the following graphic, along with a symbol indicating for which gender(s) these factors were most relevant.

The idea of a set-point on a happiness thermostat seems to make some intuitive sense. However, this research provides evidence that the choices you make (or choices that are made for you) can also have a lasting impact on your overall happiness, despite your genetics or personality traits. This could have implications on both personal and social responsibility. In theory, an individual can choose their own spouse/partner, and make the decision to prioritize their family. Similarly, public policy has some say on the rate of unemployment and increasing public knowledge of how to maintain a healthy weight.

For more about happiness, see also this earlier post.

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