Penélope Cruz had to style Salma Hayek's hair in the dark.

Penélope Cruz

Penélope Cruz

The 42-year-old 'Zoolander 2' actress has admitted she was forced to finish styling the 'Everly' star's brunette locks for a premiere, after the lights in her pals home went out and Penélope was left to perfect Salma's red carpet glamour in pitch black.

Speaking to PEOPLE about the moment the Spanish-born star turned hair dresser, she said: "[Salma] was getting ready for a premiere and her lights went out, and I had to do her hair in the dark.!"

Penélope - whose mother, Encarna, was a hairdresser - has revealed she picked up hair tips by visiting the salon her parent worked in and watching her tame women's tresses.

Speaking previously to the New York Times newspaper, she explained: "I was learning about all the treatments that they did.

"I was hiding there behind all my books, but I was studying them. I was studying human behaviour. It was so long ago, I was probably eight or nine, but I still remember."

Despite possessing this beauty talent the mother of two - who has son Leo, five, and daughter Luna, two, with her husband Javier Bardem - would never cut her own hair.

She said: "No, I don't cut it [her own hair], it's easier to do on somebody else."

Meanwhile, Penélope has revealed she is health obsessed but accepts her focus on keeping her body in optimum condition is probably excessive considering she visits a nutritional expert twice a year to check what she's deficient in and then she adjust her expensive vitamin intake accordingly.

Speaking previously, she confessed: "I really believe it's true that your stomach is your second brain. I don't take general multivitamins. I take specific, good quality ones, - that's important.

"I go to see what I might be deficient in. It's probably too often, but it's all part of my hypochondriac tendencies."