Keira Knightley has been wearing a wig for the past 5 years

Actress Keira Knightley arrives at the 87th Academy Awards in Hollywood, California February 22, 2015. (Reuters)

Keira Knightley revealed there's a downside to Hollywood glamour.

The actress told InStyle that she has been wearing a wig for the past five years because her hair started to fall out from being styled and dyed for various roles over the years.

"I have dyed my hair virtually every color imaginable for different films. It got so bad that my hair literally began to fall out of my head," the 31-year-old told Instyle.

Her solution? Wigs.

"For the past five years I’ve used wigs, which is the greatest thing that’s ever happened to my hair."

Knightley's hair has also undergone changes since she welcomed daughter Edie with husband James Righton in May.

"I have naturally crazy, curly hair, and since I've had the baby it's become 10 times thicker," she shared.