Mom: Allison Janney talks new sitcom, The West Wing and air guitar

"I'd been looking to try this format for a long time," Alison Janney replies when asked why she's decided to turn her hand to sitcom. "I thought it combined every single element of what I've trained for as an actor - starting out in theatre, working in front of a live audience, then doing films and hour television.

"The half-hour comedy schedule appealed to me and this particular comedy being helmed by Chuck Lorre, I knew that he had intentions to make this a slightly different half-hour in terms of the subject matter we were going to be dealing with."

Janney stars in Mom - a new comedy from hit-maker Chuck Lorre, the man behind Two and a Half Men, The Big Bang Theory and many more - and she has nothing but good things to say about Lorre ("He's kind of a genius") or her co-star and on-screen offspring Anna Faris ("I've just been a fan of hers for a long time and we get along like gangbusters!").

Her role as recovering addict Bonnie Plunkett has allowed Janney to embrace a new kind of character - one a million miles away from her renowned role as CJ Cregg on modern TV classic The West Wing.

"CJ was one of the best characters I've ever played in terms of being a role model for people," says the 54-year-old actress. "I'm sure Bonnie could be a role model to some people, but she's not as likeable as CJ - she's a little more abrasive and has a different way of tackling life's problems!"

Janney still speaks fondly of her time serving under President Bartlet, regaling Digital Spy with tales of lip-syncing 'The Jackal' in her trailer and playing air guitar with co-star Richard Schiff.

"You can't even believe - Richard and I are the silliest, the two of us together would do the silliest things. You think he's the most serious man on the planet but the two of us together… we just appealed to each other's juvenile tendencies."

Mom is now Janney's outlet to release her inner screwball, and she cites The Carol Burnett Show and The Mary Tyler Moore Show as her earliest comedy inspirations. "Physical comedy is my favourite kind," she says. "I've felt always as a person I'm much more able to express myself physically than verbally!

"Growing up, I was a figure skater, I did ballet and modern dance, so I'm very aware of my body and what it can do and how to fall. I live for physical comedy and I think my size [Janney stands at over 6 feet tall] just makes it more hysterical!"

But there's "real pathos" in Mom too, she insists - indeed, the show has attracted positive comment from US critics for its balance of humour and more serious subject matters. "There's nobody that isn't touched by the issues these characters are going through," says Janney.

"I think hard times are only survivable with laughter and that's what we attempt to do here. It's just going to get deeper and more complicated and I love the direction it's going in. it's enormously fun and rewarding to act with this kind of material."

Mom airs on Mondays at 9pm on ITV2.