The Wiggles finally explain why Jeff was always asleep

The new Wiggles documentary explains why Jeff was always sleeping.

Prime Video has just released the highly awaited documentary Hot Potato: The Wiggles, which looks at the child entertainment group's meteoric rise to fame.

In one scene, Purple Wiggle, Jeff Fatt explains the origins of why his character was always sleeping and his iconic tune, 'Wake Up Jeff'.

"It used to be Anthony Field that would fall asleep, and the children got to wake Anthony up. But it really suited me because it was a bit of a mask," the 66 year old said in the sit-down interview.

"I'd actually say, I'm very shy and introverted because I was the only non pre-school teacher and I had very little experience in dealing with children."

Fatt added that despite making a career as a children's entertainer, he's always struggled to be in front of an audience unless he had a 'role to play'.

"...Public speaking that sort of this, forget about it," he added.

"It was a way of getting me involved and on stage and as it turns out, it's such an empowering thing for a child to be able to wake up a grown-up," Fatt continued.

Anthony Field, famously known as the Blue Wiggle, described how he initially thought of the song idea for 'Wake Up Jeff'.

Field said that while teaching at a preschool, the children would wake up a tree.

"The tree would fall asleep, and they'd have to go, 'Wake up tree', and I thought, 'This is fantastic.' So we gave him [Jeff] the role of just falling asleep," he recalled.

Brendon Thorne/Getty Images for SXSW Sydney

Shortly after the documentary was announced, the film's director, Sally Aitken, told the Sydney Morning Herald the movie explores how the group started as pub rockers before becoming one of the most successful child entertainment bands ever.

Aitken added it has very 'universal themes'.

She said: “The film has the very deep universal themes of any heroic journey, with an unlikely group in a sea of disbelievers chasing an impossible dream, and getting there. That’s not just an Australian story, it’s what the great films are made of.

“It’s a tale of a group of friends who have dreams of rock stardom, and they don’t quite anticipate that the pathway to that is through children’s entertainment.”

You can now stream Hot Potato: The Wiggles on Prime Video.