MOST people struggling to pay off their student loans keep quiet about it. They do not want to acknowledge that, perhaps in a fit of naïve, youthful optimism, they borrowed more than they could handle.

Then there is Alan Collinge, who for years has described his struggle with tens of thousands of dollars in student loan debt to anyone who will listen. He has appeared on “60 Minutes” criticizing Sallie Mae, the nation’s largest student lender, and has been quoted in the pages of this and other newspapers attacking loan companies.

“I’m sort of the complaint box for the industry,” says Mr. Collinge, who runs a Web site called StudentLoanJustice.org out of his spartan apartment here.

Student lending is a big business, one that has been the subject of many complaints over the past two years after revelations of questionable ties between lenders and colleges’ financial aid officers. More recently, tight credit markets raised the possibility that some students might not be able to borrow to go to college in the fall.

But much less attention has been paid to what happens to students after they borrow. Lenders who make loans guaranteed by the federal government can more easily take steps against borrowers — like garnishing wages and benefits — than they can with other kinds of unsecured consumer debts. And all student loans, federally guaranteed or not, are extremely hard to get rid of in bankruptcy proceedings, more so than credit card or other debt.

More borrowers may begin to discover the harrowing consequences of reneging on student loans in the current economy. Numbers of borrowers behind on payments and in outright default are rising for some types of loans, and the tight job market makes it harder for graduates to find jobs that let them pay off debts. At the same time, investors are pressuring lenders to raise revenue by minimizing losses. Investors also expect more revenue from those lenders that operate collection agencies.

To many people, the special treatment of student loans sometimes seems appropriate, but at other times unduly harsh. Usually, people do not learn just how powerfully the law protects student loans until something goes unexpectedly wrong in their lives.

Donna Troestler, 47, who graduated from the University of Wisconsin, Oshkosh, in 1998 with a degree in biology and microbiology, was traveling to sell scientific instruments in 1999 when she suffered an injury that caused recurring problems. It took years for her to figure out what kind of work she could do, given her new health limitations; in the meantime, she deferred payments on about $23,000 in loans.

“I never thought in a million years that I was ever going to have a problem with working and making money,” Ms. Troestler said. In 2002, she defaulted on her loans, which then ballooned with fees and penalties to $63,000, she said. In 2003, she found a job at the University of Wisconsin, Madison, where she still works. But then she found that her wages had been garnished, taking about $500 a month from her $2,500 take-home pay, she said.

“All of this was terribly embarrassing to me,” Ms. Troestler said. Later, a man she was dating helped pay off her student debts, in 2006, but then the two split up because of tension over the loans, she said.

IT is hard to tell how widespread repayment problems are. The overall default rate calculated by the federal Education Department was under 5 percent in 2005, the most recent data available. But that figure includes only defaults within two years of beginning repayment.

A 2006 study by the department’s National Center for Education Statistics followed federal loan borrowers for 10 years, ending in 2003-4, and found that nearly 10 percent defaulted. (The average debt among the two-thirds of 2003-4 college graduates who use loans is about $20,000, according to the College Board.) And with more students borrowing, more students are potentially at risk.

Garrett Mockler filed for bankruptcy protection in December 2004, after months of struggling to make payments on credit cards as well as on $40,000 in student loans. He was working multiple jobs as a teacher, dancer and choreographer in Los Angeles after earning a Master of Fine Arts in 2003.

His lenders wanted more than $400 a month on top of credit card debt, Mr. Mockler said. “All my bills started piling up,” he said. “It was either pay one bill or pay another or not eat or not have a roof over my head.”

He had to scrimp to save $200 for the bankruptcy filing. Then he emerged from bankruptcy and found that all his student loans had stuck with him. While the federal government gave him more forgiving repayment terms on his guaranteed loans, he said, the company that had made him a private, or unguaranteed, loan had no incentive to negotiate a payment plan with him because he had no way to avoid the obligation.

While trying to learn more about student loans and his rights in dealing with lenders, Mr. Mockler said he came across StudentLoanJustice.org, Mr. Collinge’s site.