First, German research finds that there’s a strong day of the week effect upon happiness. People are much less happy on Sundays than other days; they side with Billie Holiday rather than Fats Domino.
You might think this is because people dread having to go to work on Monday. Not so. Even the unemployed are less happy on a Sunday than other days. Instead, the Sunday effect seems especially strong for married people, rather than singles - so strong, in fact that the difference in a married person’s happiness between Sunday and other days is over one-third the difference in happiness between the employed and jobless, which is universally found to be huge. Maybe familiarity breeds contempt. Although marriage raises well-being, sustained exposure to one’s partner - or children - does not.
Secondly, other German research (pdf) sheds light upon the finding that happiness is U-shaped in age, bottoming out around one’s 40s.
The authors suggest this is because people’s failed investments become apparent in mid-life. 40-somethings are more likely to be divorced; those who are unemployed suffer more; even quite successful people realize that they’ll not get to the top of their career ladder; children reduce parents’ well-being; and, as Marianne Faithfull sang, we learn that we'll never fulfill our dreams.
Thirdly, Italian researchers think they’ve found an explanation for the Easterlin paradox. It lies in social capital. Nations which have suffered big falls in this - as measured (or proxied?) by membership of voluntary organizations - have seen happiness fall.
There is, I suspect, a common theme here - that people don’t predict what will make them happy at all well. Having children and investing in careers rather than in social networks doesn’t make us happy, and yet we do it in our 20s and 30s, only to be miserable later.