So you know how actresses (and some actors) are constantly dying their hair for different roles? Well, turns out that’s not so great for overall hair health. In fact, it made Keira Knightley’s hair fall out!

And that’s why she’s been wearing wigs for the last 5 years…onscreen, to be clear. As she tells InStyle in a new interview, the constant processing for different acting jobs took a toll on her normally “crazy, curly hair” that it “literally began to fall out of my head.”

Along with the fake head pieces, she’s also had one other secret hair restoration weapon:

“Since I’ve had the baby,” she says of her first child, born last year, “It’s come back thicker than ever.”

One final Keira Knightley related hair fact: She also reveals she’s a huge fan of the Tangle Teaser, since it’s the only thing that works on what she calls her “dreadlock” of knotty hair.