Several years ago, a large research project carried out by a major supermarket hair brand found that a bad hair day (BHD) really does have an effect on women's mental health. A BHD doesn't just leave you feeling flat; some women reported more serious reactions - depression included.
The 3000-strong survey found that BHDs made women irritable and argumentative, and more inclined to pick fights with their partners.
Bad hair, it concluded, can get you dumped for reasons far more complicated than merely looking like a scruff. It's easy to sneer at the notion someone might feel seriously out-of-sorts because their hair isn't looking great. But research also shows that hair can lead other people to make ill-informed snap judgements about your personality and the way you manage your life.
A recent, similarly focused, study took the idea further, using eye-tracking technology, which allows scientists to observe subconscious behaviours.
They monitored people's responses to looking at photos of women with bad hair (unwashed or not brushed) and beautiful hair (professionally styled).
Most of what the survey revealed was perhaps to be expected: Women with beautiful hair were judged as younger, more professional and better looking, whereas those with unkempt locks were considered older, lazy and lacking in pride. The eye-tracker also illustrated that people were far more likely to focus on your face when your hair was gorgeous.
"Lots of people don't realise the potential a good hairstyle has to shape your image and change the way others perceive you," said Guy Roberts, a principal at Vada and one of the finalists in this year's L'Oréal Professionnel Colour Trophy competition.
"Bad hair just seems like a missed opportunity."
What's more, it could be argued that stylists perform an important social function. Part psychologist, part professional pamperer, a good one should be like a trusted friend, lifting you out of that rut physically as well as emotionally.
Essentially, it comes down to communication. Here are some tips for making sure you walk out of the salon looking (but more importantly feeling) great.
DON'T TELL PORKIES
Do not lie to your stylist and tell them that you're a pro with gadgets when you don't own a hairdryer or struggle with straighteners. If you need a cut that looks good when you do little to it other than leave it to air dry, be honest about it.
It doesn't mean you'll get it (what stylist wouldn't try to talk you into more advanced grooming?) but it will give him or her an idea of your headspace when it comes to maintenance.
"There has to be some give and take between you," says Roberts.
"Let your stylist make suggestions, but give them parameters to work within, so they can help you most effectively. Sometimes it's easier to tell your stylist what you definitely don't want."
SHOW AND TELL
Do show your stylist pictures of the looks you like. But be flexible. An image is a good starting point, giving a stylist a better chance of finding out exactly what it is you're after.
Do you really want an edgy pixie cut, or just something that's easy to manage?
Sometimes hair that looks effortless in an image is anything but.
"Pictures are ideal," says Dawn Thomson, from Rodney Wayne Whangarei.
"It makes it a lot easier for everyone and leaves no surprises at the end of your appointment."
Avoid specifics. What does "cut a couple of inches off" mean if you aren't holding a tape measure?
If you want it cut to shoulder length, say so. Pull your hair up to the place where you think it flatters your face shape.
Work together. Don't leave any room for guesswork.
DON'T ZONE OUT
Look up every now and again from that magazine to make sure things are going to plan. Now is not the time to totally abdicate responsibility.
Do not, by any means, grab the scissors and try and do it yourself, but equally, don't be afraid to ask questions if you're unsure.
"The lack of interest some people have in their hair breaks my heart," says Adrian Barclay from Venom, a salon finalist in the Colour Trophy.
"Hair is the ultimate fashion accessory, and it's how you choose to present yourself to the world. If you do nothing, you get nothing. People want to look and feel sexier but aren't prepared to do anything about it."
The best colour is the colour you can afford to maintain. If you can't spring for six-weekly touchups, go for a look that's less expensive to keep up. Ask your stylist to choose a colour that's closer in depth to your natural hair level. This means less re-growth and therefore less frequent visits to the salon.
There's an easy and almost immediate way to evaluate a new stylist. If they criticise the work of your previous hairdresser with remarks like: "Your hair is really shapeless," or "Who did this?" it might be time to reconsider the relationship before it's properly begun.
If you really loved your hair, you wouldn't be sitting in their chair - there's no need for negativity. Hair is personal; if you start off feeling criticised you are better to break up now.
MAN O MAN
Fashion trends can oscillate from one extreme to another, but when it comes to men's hair, the pendulum doesn't swing particularly far.
Short back and sides, long on top, slicked back, smoothed forward; the terminology alters little from season to season. But that doesn't mean there's no room for creativity, especially when it comes to colour.
"Colour is more subtle for men," says Vada's Guy Roberts.
"It's designed to blend, not cover. When it's lighter, the tones are still very muted and cooler."
Venom's Adrian Barclay says that "for men, colour is focused on a lot of slate, shiny grey tones. Dark matt tones with lightened tips are really hot for men this year. We're also seeing a lot of deep chocolate shades with a slight raisin tone."
- Sunday Magazine