THEY ARE BEGINNING TO CATCH ON. The backward bending supply curve is not just for the blackboard.

"Common in academia, sabbatical leave is becoming a more common tool in business," the [Society for Human Resources Management] says on its Web site (www.shrm.org). "As adapted by many non-academic organizations, sabbaticals are provided to allow employees to pursue education, engage in personal projects or attend to special family needs."

That's the analogy. Here's the context.

[Robert W. Baird's Leslie Dixon] has been in human resource management for 19 years, and in the last decade, she has seen a surge in consideration of leaves and flexible work arrangements that let employees better balance work and life.

"We have had more people asking," she said. "The more we look at it, the more we realize that, to attract and retain the best people possible, we needed to have" such policies.

The changing face of the work force also is forcing such changes, said Shelley Jurewicz, executive director of the Young Professionals of Milwaukee.

Younger employees see time flexibility as much more important reasons to stay with an employer than do most companies, she said.

"You are going to have to put energy into these emerging top benefits if you want to compete for talent," she said.

But not everybody has yet caught on. The coffee bar at the local vendor of lottery tickets and Marlboros in a box (the modal purchase of almost everybody waiting in front of me) now sells a coffee with extra caffeine.

There are some subtleties to labor force participation that call for further research.