Especially since the financial crisis began, people have been saying they’ll solve their retirement woes by working longer. The reality, according to a new study from the Employee Benefit Research Institute (EBRI), is that many leave earlier than planned.

The 2009 Retirement Confidence Survey found that 47% of retirees left the work force before they thought they would. Why the disconnect? A shrinking economy and declining health. Of those who left earlier than planned, 42% cited health problems; 34% pointed to layoffs, closures or other problems at their companies; and 18% said they had to care for a spouse or other family member.

Since working longer is one of the easiest ways to boost a shrunken portfolio (or one that was never big enough to start with), this new data is another troubling sign for Americans’ retirement readiness.