Gwyneth Paltrow loves to rap like a ''bad mutha''.

The 40-year-old actress admits her husband, Coldplay frontman Chris Martin, can't bear to listen to music when he is at home, but as soon as he goes out, she puts on her favourite hip-hop records and heads into the kitchen.

She said: ''He can't have background music on; it has to be 100 per cent of his attention.

''But if he isn't at home, I turn on the hip-hop - I'm like a bad mutha rapping along to every word as I cook.''

Gwyneth - who has children Apple, eight, and Moses, six, with Chris - also admitted she is a ''perfectionist'' who regularly struggles to sleep because she is plagued by ''dumb'' concerns.

She told ES magazine: ''The dumbest things [keep me awake]. I am a perfectionist. It's a very neurotic impulse. I could stress about anything from a typo on my website to juggling all my upcoming tasks at once. I find I'm pretty mellow during day, but when I get to bed my heart starts beating and I stress out.''

And despite her health-conscious persona, the 'Iron Man 3' actress admitted she still smokes the occasional cigarette.

Asked what she bought with her first pay cheque, she said: ''Probably cigarettes. I still buy the occasional pack.''