However, some sports physicians argue that sleep aids have a legitimate role in elite sport.
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When taken with energy drinks or alcohol, sleeping drugs can produce an amphetamine-like high, without falling foul of anti-doping rules.
"This represents a ratio of less than 0.01 per cent of packs sold," a Sanofi spokesperson said.
His comments come as the NRL begins testing players for the sleeping pill Stilnox and other prescription drugs, in addition to existing tests for steroids and other performance-enhancing substances.
John Mayhew, the doctor for the Auckland-based New Zealand Warriors, says he also believes the problem exists in other codes.
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"He won't say so and he doesn't look for excuses but I feel for sure it did," he said.
However, Dr Larkins says if doctors are prescribing Zolpidem responsibly, and patients are taking it for short periods only, there should not be a problem.
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First posted March 18, 2014 19:36:01.
Updated March 19, 2014 11:09:38.
However, under a new policy club doctors will no longer prescribe it, and if a player returns a positive test, he will initially be counselled against using it.
It's the people that are habitually using Stilnox the wrong way that have given it its bad reputation.
"It's the people that are habitually using Stilnox the wrong way that have given it its bad reputation.".
Topics: drug-use, drug-education, drugs-and-substance-abuse, sport, rugby-league, nrl, australia, new-zealand.
in other codes as well. I think it's a problem which is involved in the NRL and also. Widespread is the word I'd use.
"Basically they get a high and it doesn't contravene any of the existing drug testing protocols," Dr Mayhew told 7.30.
They just don't get the rest, and unless you are going to meditate or count sheep, sometimes doctors will give them, in the short term, a sleeping tablet to help them get settled into their normal sleeping pattern. "They often say they replay the competition in their head.
He said that after discussions with players and other club doctors, he believed "cocktailing" sleeping drugs with energy drinks and alcohol was "widespread" in the league.
Sam Sorrenti, a spokesman for the NRL Doctors' Association, says sleeping drug abuse is not common in the league, but "we would rather stop it before it becomes a problem".
"Clearly it's got side effects. but that manifests itself so quickly that you stop using it and find the alternative," he said.
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I think it's a problem which is involved in the NRL and also, following discussion with people in other codes, it's a problem in other codes as well.". "Widespread is the word I'd use.
Among them is Dr Peter Larkins, a sports physician and former Olympian who has worked with AFL players and other elite athletes for decades.
NRL chief operating officer Jim Doyle said testing for Zolpidem and depressant drugs Benzodiazepines this season is for data gathering purposes only.
"You do that continuously for 10 years of your career it's impossible, if the substance you're taking happens to be addictive, you're not going to be addicted to it," Cotterell said.
Given Zolpidem is not prohibited under World Anti-Doping Agency rules, it is unclear exactly what sanctions could apply.
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"If they test positive for a second time, the full brunt of the law will be applied to them," Dr Sorrenti said.
“By the end of the year we will know if prescription drugs are being abused in our game and we can take steps to remedy the problem.".
Swimming Australia's doctors no longer prescribe Zolpidem, and the body supports the Australian Olympic Committee's ban of the drug.
After the men's 4x100m relay team admitted to taking Stilnox in a bonding session ahead of the London Olympics, it was revealed that swimmers competing at an international level had been regularly prescribed the drug to help them sleep.
"It's a problem in Sydney, to a lesser extent in New Zealand, and certainly the non-Sydney clubs as well," he said.
Professor Phelps says she has seen multiple patients who have all experienced dangerous effects from Zolpidem, such as sleep-walking on high-rise balconies, and says a full ban on the drug for the general population should be considered.
"Athletes are often wired up, they are balancing a lot of things, certainly the night-time training and the night-time competitions," he said.
His former coach Denis Cotterell told 7.30 he believed use of the drug contributed to Hackett's failure to win a gold medal at the Beijing Olympics.
The NRL has not formally banned Zolpidem, the generic name for Stilnox, which is also sold under the brand names Ambien, Intermezzo and Stilnoct.
AEST = Australian Eastern Standard Time which is 10 hours ahead of UTC (Greenwich Mean Time).
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Dr Sorrenti says the NRL will likely move to formally ban Zolpidem next year.
"We want to find out if we do have a problem with prescription drugs in rugby league because, at present, there is only anecdotal evidence," Doyle said in a statement.
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Grant Hackett's manager said the Olympian had been admitted to rehab in the United States earlier this month because of a dependency on Stilnox.
" is an over-reaction because of bad behaviour of a few individuals.".
Sanofi, the company which makes Stilnox, says last year its "adverse event reporting centre directly received 24 individual reports of suspected adverse events from consumers taking Sanofi's Zolpidem products".
The practice of mixing sleeping pills with alcohol and energy drinks is widespread in the National Rugby League, a club doctor has told the ABC.
But prominent GP and former head of the Australian Medical Association, Professor Kerryn Phelps, says athletes "stay right away from Stilnox".
"The potential side effects are potentially life-threatening. It has been attributed to deaths, and I think we need to be very careful about balancing risks with benefits," she said.
Stilnox has gained notoriety within the sporting world because of its abuse by a number of Australian swimming stars.Stilnox