Rudd speech lulled the powerful to sleep

Kevin Rudd bored many an Australian voter for years with his long speeches and impenetrable language.

Now it has been revealed one of the former prime minister's lectures put one of the world's most powerful men to sleep.

In his recently released memoir, former US defence secretary Robert Gates says on a visit to Australia in 2008, he fell asleep while listening to Mr Rudd.

Mr Rudd had just begun an address about Australian history when the defence secretary nodded off.

Mr Gates, who was in Australia then as part of yearly AUSMIN talks, had recently had a fall and broken his shoulder.

"At a very nice dinner given in my honour by Australian prime minister Kevin Rudd, I was doing fine at table conversation until Rudd began a long soliloquy on the history of Australia," he writes.

"I had made it just past World War I when the combined effect of a painkiller, jet lag, and a glass of wine caused me to fall asleep. This led to not-so-subtle attempts by my American colleagues at the table to rouse me."

Mr Gates said Mr Rudd was "very gracious" about the situation. Yesterday, a spokeswoman for Mr Rudd said he was surprised Mr Gates could remember anything from the night.

Mr Gates, who was taking medication for his broken shoulder, "should have taken up Mr Rudd's suggestion . . . to forget dinner and just go home to bed", Mr Rudd's spokeswoman said.

Mr Gates' memoir Duty has caused headlines in the US with the former military chief making plain his disappointment in President Barack Obama.