Researchers in WA are asking university and TAFE students to take part in an online survey on so-called study drugs.

The National Drug Research Institute said not enough was known about substances which some students believed help them study.

Project leader Simon Lenton said while the drugs might be useful for treating certain conditions, their effects on healthy people were not so clear.

"There's been a couple of projects done in the eastern states which we've found [use] rates ... around 4 to 8 per cent but in the US they've found much higher rates of use and we really don't know what's happening," he said.

"So although there have been some reports about from unis and so on, we're really not sure, and that's one of the reasons why we're doing this work."

'What's in the tablet, might not be what's on the box'

Professor Lenton said the substances ranged from herbal remedies through to prescription medications and illegal drugs.

He said some of those who used the drugs researched them, and or accessed them, via the internet which potentially had serious legal and health implications.

"Some of these medications can have adverse effects if taken over long periods of time or not under prescription or monitoring by a doctor," he said.

"And what's in the tablet might not be what's on the box."

Professor Lenton said it was not clear how useful the drugs were to students.

"There's sort of anecdotal reports of people doing all-nighters thinking that they're getting ready for their exam or whatever and then actually going into the exam and not performing very well at all," he said.

"We don't know how effective they are, we really want to find out the extent to which students are using these drugs and also to find out what their attitudes are to the use of these drugs as well."

Professor Lenton said students who did not use study drugs were also being asked to take part in the online survey.

The survey, which can be accessed via the NDRI Curtin University website, is anonymous and the results are confidential.