The 43-year-old actress - who is renowned for her pale skin and blonde hair - has had to rid herself of her locks before and is considering doing so again because she finds it "liberating".
She said: "Shaving off my hair is so liberating. I had to do it once for a film role, but I`ve done it periodically too.
"At school it was probably to rebel, but I cut my hair short a few years ago and I`m thinking about doing it again."
The Australian beauty - who has children Dashiell, 10, Roman, eight, and four-year-old Ignatius with husband Andrew Upton - tries to avoid the gym as much as she can as she likes to get her workouts done while doing her job.
She added: "I try to be healthy but I find exercise deathly dull. It tends to be easier to get outside in Australia, but the rain and floods have been atrocious in the past few years which limits things.
"Luckily, work keeps me fit and I`ve just been on stage with a show that`s very physical, which staves off the gym for a bit longer."