Manly star Anthony Watmough has admitted to using Stilnox and claims an incident involving the controversial sleeping pill led to his four-year exile from the NSW Origin team.

The Sea Eagles back-rower represented NSW in the 2005 series but wasn't picked again until 2009.

He believes the reason behind his omission was a drug-induced episode during his debut Origin series in 2005 where he was found wandering the team hotel after taking the sleeping pill.

"I had a couple (of pills) and didn't know what they were doing and went sleepwalking," he told Triple M on Wednesday night.

"The rest is history...I had a (four) year exile."

Asked his recollections of the night in question, Watmough said: "I don't know. I have no idea. I remember, vaguely, bits.

"I was out near the pool and had locked myself out (of my room) and couldn't get in.

"No-one said anything (about being exiled). I only knew what I read in the papers so someone was obviously saying something.

"I'm just lucky that I got a second chance and I'm back in there and hopefully win it for the Blues next year."

Watmough's admission is sure to bring the use of Stilnox back into the spotlight.

Stilnox created headlines earlier this year when the Australian Olympic Committee banned prescription sedatives such as Stilnox prior to the London Games following revelations by former swimmer Grant Hackett he had used it throughout his career and it's use was rife among the Australian swim team.