Via the MetaFilter discussion on the happiest man in America:

Ask a bunch of 30-year-olds and another of 70-year-olds as Peter Ubel, of the Sanford School of Public Policy at Duke University, did with two colleagues, Heather Lacey and Dylan Smith, in 2006 which group they think is likely to be happier, and both lots point to the 30-year-olds. Ask them to rate their own well-being, and the 70-year-olds are the happier bunch. The academics quoted lyrics written by Pete Townshend of The Who when he was 20: “Things they do look awful cold / Hope I die before I get old”. They pointed out that Mr Townshend, having passed his 60th birthday, was writing a blog that glowed with good humour.

Mr Townshend may have thought of himself as a youthful radical, but this view is ancient and conventional. The “seven ages of man”—the dominant image of the life-course in the 16th and 17th centuries—was almost invariably conceived as a rise in stature and contentedness to middle age, followed by a sharp decline towards the grave. Inverting the rise and fall is a recent idea. “A few of us noticed the U-bend in the early 1990s,” says Andrew Oswald, professor of economics at Warwick Business School. “We ran a conference about it, but nobody came.”

Since then, interest in the U-bend has been growing. Its effect on happiness is significant—about half as much, from the nadir of middle age to the elderly peak, as that of unemployment. It appears all over the world. David Blanchflower, professor of economics at Dartmouth College, and Mr Oswald looked at the figures for 72 countries. The nadir varies among countries—Ukrainians, at the top of the range, are at their most miserable at 62, and Swiss, at the bottom, at 35—but in the great majority of countries people are at their unhappiest in their 40s and early 50s. The global average is 46.

The Economist: Age and happiness: The U-bend of life