Seven out of 10 college students say it is somewhat or very easy to obtain controlled stimulants without a prescription, according to a new survey conducted on eight U.S. campuses.

About 18 percent of undergraduates reported misusing prescription stimulants such as Adderall, the 2015 College Prescription Drug Study (CPDS) found. The great majority (83 percent) received them from friends and most said they used the drug to help them study or improve their grades.

While stimulant use was most common, students are also misusing a variety of other prescription medications, according to the survey.

“Overall, one in four undergraduates reported that they used prescription pain medications, sedatives or stimulants for non-medical reasons in their lifetimes,” said Anne McDaniel, author of the study and associate director of research and data management at The Ohio State University’s Center for the Study of Student Life.

Approximately one third of students said it was easy or very easy to obtain pain medications. In addition, approximately 9 percent of undergraduates used sedatives, with 44 percent saying it was easy or very easy to find them on campus.

“At one time, college students most commonly misused drugs to get high,” Hale said.

“But today, students also use medications to self-medicate, to manage their lives. They are using drugs to control pain, to go to sleep, to relieve anxiety and to study.”

For example, 55 percent of students who misused pain medications said they did it to relieve pain, while 46 percent said they did it to get high. More than half who misused sedatives said their aim was to get to sleep, while 85 percent who misused stimulants wanted to improve grades or studying.

Marijuana was the most common illicit drug replacing prescription medications, used by half of undergraduates who misused controlled drugs, followed by cocaine and hallucinogens at 19 percent.

Nearly two percent had used heroin.

“There’s been a lot of media attention given to the recent rise in heroin use and for good reason,” he said.

The CPDS was conducted in spring 2015 by Ohio State’s Center for the Study of Student Life in cooperation with the university’s Higher Education Center for Alcohol and Drug Misuse Prevention and Recovery (HECAOD).