Longitudinal evidence for a midlife nadir in human well-being: results from four data sets

Summary

There is a large amount of cross-sectional evidence for a midlife low in
the life cycle of human happiness and well-being (a ‘U shape’). Yet no
genuinely longitudinal inquiry has uncovered evidence for a U-shaped
pattern. Thus, some researchers believe the U is a statistical artefact.
We re-examine this fundamental cross-disciplinary question. We suggest a
new test. Drawing on four data sets, and only within-person changes in
well-being, we document powerful support for a U shape in longitudinal
data (without the need for formal regression equations). The article's
methodological contribution is to use the first-derivative properties of
a well-being equation.