For the last 20 years, ‘Jen An’ has been the biggest tress-setter in Hollywood. She gave Beauty Bible a rare interview about that super-famous mane and getting involved with Living Proof, her new haircare range If there’s one woman who has made hair history it’s Jennifer Aniston – no contest. Although she doesn't ‘really follow trends’, she told us, she sure as anything sets them. ‘The Rachel’ (created in 1994 for her role in Friends, as if we could ever forget) became one of the most requested styles of all time – though Jen has since admitted ‘that damn Rachel… was not my best look’.

Since then, she’s been long, short, straight, wavy, layered, blunt cut, parting in the middle – or at the side, up/down, in a pony tail – you name it, she’s rocked it. But, she told us, ‘I just feel most like myself with loose, understated hair. That’s why I tend to wear my hair down on the red carpet’. (And, rather comfortingly, she has had total hair disasters, both in public and private - ‘yes and yes!’)

For every day, she says, her naturally wavy hair is ‘pretty low maintenance. I wash it every two or three days, even with workouts. It’s so damaging to wash your hair every day. I tend to wear it either straight – I used to be hopeless with a blow-dryer but now I am pretty good - or with a bit of a beachy wave to it. When I let it air dry, it has some texture to it’. Her quick fix when she’s late and got to look good, by the way, is ‘a ponytail or a bun’.

The man behind the most-famous-hair-in-the-world is Los Angeles stylist Chris McMillan. ‘I’ve been going to Chris for 20 years and he’s been my friend that long too. We have a lot of history between us,’ says Jen. ‘When I was 25, my manager suggested I go to Chris. He does amazing work, and apart from being an artist he is a wonderful person. The hair and beauty industry is very competitive. It’s rare to find someone who has a warm heart like Chris.’ No surprise then that Chris has now joined Living Proof, the range that Jen co-owns, as Celebrity Hairstylist.

Living Proof was just one in a long line of hair care companies that wanted Jen on board. ‘I’ve always said no but this time it felt different. I tried their No Frizz products on the set of a movie I was filming down in Wilmington, North Carolina where there was maybe 100 percent humidity. I thought this would be the perfect test to see if the products actually lived up to their claims. And they did. I couldn’t believe it. It was the most wonderful experience. My hair stayed smooth, and it was so easy to do.’

Although Living Proof trumpets its scientific approach, the boffins there are pretty ‘out of the box’, according to Jen: ‘they come up with a lot of wacky but brilliant ideas’. Jen and Chris are far from being figureheads. ‘We definitely share any ideas we have [and] they’ll send me lab samples to test out, and I have helped with some fragrance and packaging decisions. I actually worked on those for our Curl line, which is just coming out in the UK. That was a lot of fun.’

Product wise, Jen switches between No Frizz and Restore. When I’m not working I’ll put No Frizz Nourishing Cream in my hair and let it air dry. I also like Amp [instant texture volumizer] a lot to add a little “grit”.

Her biggest revelation is that hair ages. ‘Did you know that?‘ she asks. ‘As we get older it doesn't necessarily react as beautifully as it used to in our 20s. The Restore Mask is just incredible – I use that every Sunday. It has completely transformed my hair.’

How important, we asked her, is the state of your hair to a woman? Is it really the difference between a good or bad day? ‘It’s just hair – it shouldn’t be so important. But we all know how having a good hair day just makes you feel better. That’s why Living Proof resonates with me. They’re using science to help you have more good hair days, so you can get on with your life and what’s important to you.’

You can find Living Proof in the UK at SpaceNK here - and watch this space for a chance to win products from the range, with a prize draw on our site running for five weeks from 2nd June 2015...