Why is Cheryl Tweedy's hair always so friggin big?

Everytime I see Cheryl Tweedy on TV her hair is SO BIG!! I feel sorry for that mop of brown hair on her head, it must be torture. And her hair looks great when it's tied back normally. I was just watching Girls Aloud Live At Wembley on TV and it's not just her!! Kimberley and Nicola's hair was ridiculous. I know loads of people are probably gunna have a go at me cos they LOVE Girls Aloud but you can't tell me you've never noticed...