Bradley Cooper and Robert De Niro star in Limitless, a paranoia-fueled action thriller about an unsuccessful writer whose life is transformed by a top-secret "smart drug".

IT'S the real life "limitless" drug - touted as Viagra for the brain - that shot to prominence when a Silicon Valley millionaire credited it with his amazing success.

Now news.com.au has discovered the drug is being purchased online and obtained by Australian workers in high pressure industries such as finance to stay ahead of the competition.

A number of workers who spoke to news.com.au on the condition of anonymity said the use of the drug had grown among workers in competitive, fast-paced industries in recent months.

Modafinil, marketed as Provigil in the US, is a prescription-only drug used to improve wakefulness in those who suffer from sleep disorders like narcolepsy.

It shot to fame when Dave Asprey, the founder of The Bulletproof Executive and self-described "biohacker" credited the use of Provigil to his success in Silicon Valley.

"I started taking it when I was getting my MBA while working full time at a start-up we sold for $600 million," Mr Asprey told news.com.au.

"I ended up taking it pretty much every day from 2001 to 2009. I think it's been an enormous boost for my career and even my family, having limitless energy and focus is amazing."

It's since been popularised as the real-life version of the drug used in Limitless, the 2011 film starring Bradley Cooper, and has gained a cult following among financial traders, IT professionals, poker players and card-counters.

"I think it's a combination of being in a mentally tiring job with a lot of competition and a workload much larger than there are hours in the day," said one Sydney finance worker, 35, who had tried the drug after reading about it online.

"The stories I read were all very positive and being in a busy stressful job with not enough time it's exciting to think there might be something that can give you and edge on the competition, but mostly to combat exhaustion.

“It’s really hard to say [how many people use it] because people don’t want to admit. Part of the idea is the higher up the corporate structure you are, you don’t want to give away your secrets or anyone to accuse you of not doing it on your own."

Dave Asprey said he has received inquiries from Australians about how to import the drug or how to obtain it online.

"I'm not an expert on Australian law but I am on Provigil. I do know for a fact that you can import it and some people are on it and enjoying it."

One Sydney worker who spoke to news.com.au said the drug provided him with a high level of energy and focus for his job. He said it was like having a major coffee hit, without any caffeine jitters.

"I find if I have coffee there's an immediate energy burst but it wears off quickly and is often accompanied with some anxiety or nervousness. It's a much more consistent eight or nine hours of evenly keeled energy and focus," he said.

"Rather than a conscious feeling of energy, you notice in hindsight that you didn't get tired and you worked for longer than usual. It's more like ‘oh wow it's been two hours and I haven't looked at the clock."

Another executive worker, 27, who runs his own creative agency, said he was first tempted to try the drug after hearing about its benefits from colleagues and reading about it online.

He had heard that he could use it to gain consistent focus for 12-14 hour days.

"When I first heard about and weighed up how it could affect me, I thought it would be a wonder-drug that would make me more creative but it doesn't do that at all," he said.

"It gives you mental endurance. It doesn't make you mentally more creative. It just pushes you further in terms of the amount you can get done…. If you've got a to do list you'll smash through it no questions."

Australian Medical Association President, Dr Steve Hambleton issued a severe warning against Modafinil, saying it was illegal to use or import the drug without a prescription and could lead to huge risks when not taken appropriately.

"There are dangers if you're pregnant or likely to become pregnant. If you're under 18 or over 65, if you've got a mental illness or for people with abnormal heart rhythms. There's an interaction with anti-depressants, there's an interaction with drugs that help epilepsy and blood-clotting drugs," he said.

But while users who agreed to speak to news.com.au said the initial benefits of the drug had been positive all agreed they would no longer use the drug daily.

"There's no such thing as a free lunch. While Dave Asprey says it has no side effects, there's got to be something. I wouldn't be comfortable taking it every day. You still feel like you're affected by something," the finance worker said.

Dr Hambleton said it's crucial people don't believe online hype, and that the best way to focus at work is to get a good night's sleep.

"This is a serious drug with serious side effects" he said.

"There's headaches, vomiting, aggression, anxiety depression, uneven heartbeat. Get a good nights sleep and eat well, exercise and that's the best advice we can give. If it sounds too good to be true it probably is."