She’s a dressed-down, seriously smart cookie in ‘CSI: Crime Scene Invesigation’, but off-screen, Jorja Fox loves to get glammed-up for big nights out in Hollywood.

Brains and beauty can mix. That’s if vivacious American actress Jorja Fox, 34, is anything to go by. The ex-model plays Sara Sidle, a bookishly sexy forensic scientist in Channel 5’s number-one show, CSI: Crime Scene Invesigation, which also has the second biggest TV ratings in the US. But life on screen is more grit than glamour, with Sidle spending most of her time at Las Vegas murder scenes. “I’m more into make-up than Sara would be; she’s practical, although she certainly flirts with the guys,” Fox laughs.

In CSI, your character has very straight hair, yet yours is naturally curly. How come?

I associate her with action-figure qualities: sleekness and stelth and, for me, straight hair reflects that. I use Phillip B Straight Baume [£16 ; from Space NK, 0870 169 9999], and straightening irons every day.

What do you do with your hair off duty?

Mostly, I wear my hair curly, partly to give it a rest because I straighten it every day at work. So I’ll let it do it’s own thing.

Your character is quite no-nonsense, but is she feminine? Does she like make-up?

The characters are almost always on the job, so you see her in work clothes. Sometimes she has to go to dark, creepy places - sewers, deserted roads, and under people’s houses - so she wears lots of jeans, boots and long coats. Crime scenes are dangerous places. Often criminals return to the crime scene, so she needs clothes she can run in! Make-up wise, she likes low-key lips and smoky, mysterious eyes to reflect the intense, brooding vibe of her character.

Now that CSI is so successful, you must have to go to awards ceremonies and dress up.

Yes, we have been invited to awards ceremonies, which is nice and it’s exciting to achieve the recognition. Getting ready to go is really fun and I enjoy havign my hair and make-up done. I always wear a classing gown and the full hair and make-up works.

Are you a beauty junkie?

Yes, I love the natural beauty of women and I think make-up is fantastic when it’s work for fun, to feel different or to create characters. But if people feel they need to wear it before they can present themselves to the world, then I feel sad for them. All shapes and colours and sizes are beautiful.

What’s your favourite make-up look?

I love the dewy, healthy look. For me, it’s all about looking alive and fresh but, for going out in the evening, I love the old-school glamour look with vampy eye make-up.

So, what have you got in your make-up bag?

Christian Dio Teint Diorlift Concealer [£15 ; available nationwide], I normally don’t leave the house without putting some on, a MAC brown eyeliner [£9 ; 020 77534 9222] and brow pencil, although I wear black eyeliner if I’m going clubbing. On a night out I’ll also wear mascara and lipgloss. I love Stila Lip Glazes [£18 ; from Space NK], and Paula Dorf Lipsicle lipglosses [£13 ; from Dickins & Jones; 020 7734 707]. I keep it simple on skin as I wear power and foundation all day and I like to give my skin a break.

How do you cope with the punishing schedule on CSI?

Normally it’s 12 to 15 hours a day, but we do get days off and three-day weekends occasionally. If I am especially tired, they’ll right me a lighter episode.

How do you keep up your energy?

Coffee, coffee and more coffee. Also, I try to get at least eight to 10 hours sleep. My social life has gone out the window. But I try to keep my energy up by eating well- lots of fruit, vegetables and protein. I eat a lot of those protien bars, too. I’m a vegetarian, not so much for health reasons but because I live in the big city, where there’s plenty of food, I don’t see the need to kill animals to eat.

What do you do to disguise tiredness?

We have genius make-up artists who put us back together, but I drink tons of water to prevent dehydration and puffy eyes.

Do you have any beauty rituals?

Oh yes, I love the bath. I’ll put essential oils in the bath and play a little music.

How do you relax?

We get time to relax on set, so I go to my trailer and play guitar. The Winnebegos go everywhere with us and I take all my tapestries and games and cars, and I have a dog, so I take him with me. LA is very much an outdoor culture, so I go to the beach and to the mountains with my dog.