Diane Kruger believes sleep is the key to looking your best.

The 35-year-old actress - who is in a relationship with former 'Dawson's Creek' star Joshua Jackson - admits she has a simple beauty regime, though it can sometimes be quite difficult to maintain, especially when she is making a movie.

She said: "I try to get nine hours of sleep a night. It's really that simple. Of course, it's hard to do sometimes, especially when I am working, but I feel and look better when I sleep well. I also noticed a great improvement in my skin when I gave up smoking.

"There are no secret potions, though."

Diane has her own beauty icons, but prefers women who maintain a simple look instead of a lavish one.

She added: "I have always liked interesting people. I trained originally as a ballet dancer so I have always admired the simple elegance of the ballerina, the refined features and serenity, and hair pulled back in a bun.

"I like a simple, clean look rather than elaborate beauty. Grace Kelly and Romy Schneider both inspire me."