Former Olympic swimmer Grant Hackett had to be restrained by staff on a flight to London in 2005 after taking the sleeping drug Stilnox, a former Qantas flight attendant has revealed in a new book.

Owen Beddall, a flight attendant who spent 12 years working for Qantas, alleges that Hackett had to be restrained by staff after storming into the first class section demanding that he be upgraded.

He also attempted to unzip his fly and urinate in the first class area, allegedly affected after taking the sleeping sedative Stilnox, according to a Daily Mail report.

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“Eventually, we wrestled him into the toilet; let’s just say it was like getting a thoroughbred horse into a racing barrier,” says Beddall in a new tell-all memoir Confessions of the Qantas Flight Attendant.

“Although I’d heard that some people had bad reactions to Stilnox – even sleepwalking – this was truly bizarre behaviour.”

Hackett’s Stilnox addiction became public earlier this year after he checked himself into a rehab facility in Arizona.

He made headlines in February after photographs emerged of Hackett walking around Crown Casino in a state of undress, anxiously looking for his young son who had gone missing.

Beddall alleges that Hackett’s ex wife, Candice Alley, who was also on the flight, handed him the packet of Stilnox and asked him to hide it.

The 34 year old has recently returned to the public eye, taking up a new role of co-host Channel Nine’s Wide World of Sports.