The Mid-Life Trough
According to this NBER paper, the mid forties are the nadir of well-being:
Recent research has argued that psychological well-being is U-shaped through the life cycle. The difficulty with such a claim is that there are likely to be omitted cohort effects (earlier generations may have been born in, say, particularly good or bad times). Hence the apparent U may be an artifact. Using data on approximately 500,000 Americans and Europeans, this paper designs a test that makes it possible to allow for different birth-cohorts. A robust U-shape of happiness in age is found. Ceteris paribus, well-being reaches a minimum, on both sides of the Atlantic, in people’s mid to late 40s. The paper also shows that in the United States the well-being of successive birth-cohorts has gradually fallen through time. In Europe, newer birth-cohorts are happier.
Whatever the cause, it appears that the “mid life crisis” might be real. The question is, Why? Dunno. Subjectively, as someone whose 40s have just begun, I feel a greater sense of well-being than ever. Perhaps because my baseline was so low….
On a more positive note, as the Danes seem to understand, one key to happiness is low expectations. Thus, by expecting to hit this trough, you may be pleasantly surprised.