(CNN) -

Nearly one in five Ivy League college students say they use stimulants to study and many don't see a problem with it.

Researchers analyzed responses from about 600 students without ADHD, and 18 percent of them said they misused ADHD medication.  One-third of those students didn't think using stimulants was cheating.

Experts are urging schools to take action.

This study was presented at the Pediatric Academic Societies (PAS) annual meeting in Vancouver, British Columbia, Canada.