Sienna Miller is ''exhausted'' by parenthood.

The 'American Sniper' actress finds being a mother to three-year-old Marlowe - her daughter with former fiance Tom Sturridge - ''incredible'' but wishes she was better at ''managing'' her life so she didn't feel she had to be constantly on the go.

She said: ''Obviously when you have a baby it's the most incredible experience but your life is also catapulted into this chaos and you are exhausted.

''I could literally get on this table and fall asleep. I'd like to be better at managing things; I'd like to be more super - although we're never going to feel it, even if we are.

''That's the curse of motherhood - we just run ourselves ragged. I'm just trying to get a sense of what that guilt is. I sometimes feel like it's a totally invented emotion. It's strange to be punishing ourselves this way. It's not healthy.''

The 33-year-old beauty is ''really close'' to her mother and sister Savannah, but admitted they also ''drive her nuts'' on occasion.

She told the new issue of Britain's Vogue magazine: ''I'm really close to them, they are hugely important and influential women in my life, but of course we drive each other nuts as well!''

Despite being regarded as a style icon, Sienna insisted she doesn't make much effort with her wardrobe these days.

She admitted: ''I don't remember the last time I went shopping. I swear to God, I wear jeans and trainers and a T-shirt most days.''