Amanda Seyfried washes her hair once a week.
The 'Ted 2' actress confessed she doesn't like to wash her hair too often when quizzed about how she keeps her long blonde locks in such good condition.
She said: "Shampoo and conditioner once a week - dry shampoo the rest of the time."
The 29-year-old star - who famously suffers from anxiety - also revealed her secrets for making her skin glow.
Amanda explained: "Every morning I wash my face with Cle de Peau cleansing foam, then the toner, then the cream. At night I do the same - I wash my face and put the cream on super-thick. Then, right before bed, I put a little lavender on my nose - it calms me, especially if I'm feeling anxious."
The 'Mamma Mia!' actress tries to avoid caking make up on her face every day and instead protects her pale skin with sun block.
She told Look magazine: "In the day I wear nothing on my face apart from sunscreen. I'm constantly applying it because I am outside in the park every day so I get a lot of sun. In the evening, if I'm doing [strong] lips just a little mascara, and then if I do a smoky eye, it's nude lips. That's the rule!"