About 13 percent of the population today is 65 or older; by 2030, when the last of the baby boomers are 65, that rate will have grown to 18 percent. In addition to testing the sustainability of entitlement programs like Social Security, this wholesale redefinition of old age may also include a pervading sense that life has been what might technically be called a “bummer.”

A study by two sociologists, Julie Phillips of Rutgers University and Ellen Idler of Emory University, indicates that the suicide rate for middle-aged people, notably baby boomers without college degrees, rose from 1999 to 2005. And Paul Taylor, the executive vice president of the Pew Center, summed up a recent survey of his generation this way:

“We’re pretty glum.”

This gloominess appears to be linked to the struggling economy, the demands of middle age and a general sense of lofty goals not met by the generation that once sang of teaching the world to sing in perfect harmony, and then buying it a Coke.