It was a bonding session that involved prank phone calls, knocking on doors late at night and other acts of “harmless fun”. The men’s 4x100m Olympic freestyle relay team made it sound like they were boys at a high school camp. But the swimmers, including Olympic medallists James Magnussen and Eamon Sullivan, admitted in a press conference yesterday that they also took the drug Stilnox – a substance banned by the Australian Olympic Committee (AOC).

Zolpidem (sold as Stilnox in Australia) is a prescription drug for the treatment of insomnia. So what role does it play in the lives of elite athletes?

In elite sports that require frequent international travel, such as swimming, Stilnox may be prescribed to help athletes cope with changes in their sleep cycle.

Stilnox is used for related reasons in other professional sporting leagues. There has been a shift towards playing matches at night to gain larger crowd attendances and higher television ratings. This means matches are not completed until late in the evening and are often followed by warm-down recovery sessions, media conferences, and travel. Some players report that the adrenalin high after a night match can make it difficult to sleep and get enough rest.

But is the use of Stilnox under these circumstances treating an underlying disorder? Or is it simply the use of prescription drugs by otherwise healthy people to facilitate an unhealthy aspect of their lifestyle?

The prevalence of Stilnox use among elite athletes is unclear but media reports over the past three years have suggested it is prescribed to a number of athletes in rugby league, rugby union, Australian rules football, and in professional sporting leagues overseas such as the National Hockey League.

In July 2012, Olympic gold medallist Grant Hackett and another team mate reported that Stilnox was often prescribed to swimmers.

We should be concerned about the routine use of Stilnox by athletes (or anyone else) for extended periods of time. There are a number of well-documented and dangerous side effects of Stilnox when used in these ways. In the United States, it is not approved for long-term use by the FDA. And according to a warning issued by the Australian drug regulator, the Therapeutic Goods Administration:

Zolpidem may be associated with potentially dangerous complex sleep-related behaviours which may include sleep walking, sleep driving and other bizarre behaviours. Zolpidem is not to be taken with alcohol. Caution is needed with other CNS depressant drugs. Limit use to four weeks maximum under close medical supervision.

Routine use of Stilnox raises the danger of addiction that can arise from cycling between using “uppers” (such as caffeine and energy drinks) and “downers” like Stilnox. Several coaches, commentators and administrators have warned players about the dangers of taking mega doses of caffeine before games because of the risks of dehydration and dangerous fluctuations in blood pressure when caffeine is combined with sleep medications.

The revelations of the swim team point to other unwanted consequences of the widespread use of Stilnox by sporting teams: diversion of prescribed drugs for recreational use. Two of the swimmers, veterans Sullivan and Matt Targett, filled prescriptions for the drug before the AOC ban came into effect and offered their pills to their younger team mates as a form of “bonding”.

Stilnox is not a banned drug so its use does not constitute a doping offence. This may make it attractive for recreational experimentation by young, male athletes wary of using other drugs prohibited by the World Anti-Doping Agency. The recreational use of Stilnox is also gaining popularity in the general population to produce euphoria, heighten sexual experiences, and to ease the “come down” after using amphetamines or cocaine.

Other elite athletes have allegedly used Stilnox recreationally. In 2009, for example, there were reports that the Queensland State of Origin rugby league team’s poor performance in the third match of that series was partly the result of players partying before the match on a cocktail of Stilnox and energy drinks. Since then some rugby league teams have explicitly banned their players from abusing Stilnox or providing it to others.

As with other prescription drugs, we should be concerned about the diversion of Stilnox and the dangers of use without medical supervision. Proper recovery from training and competition is important for peak performance.

When used short term Stilnox can usefully treat insomnia in some athletes. But it should not be used regularly to facilitate lifestyle choices.