A lot of us have a hair-washing schedule to make sure our hair looks good on the right days, while keeping the amount of time we actually have to spend washing it to a minimum.

But how often should you actually wash your hair? And what happens to your hair after it's been assaulted with shampoo? It's high time the experts weighed in.

Here, consultant trichologist Stephen Carson and Lisa Gilbey, administrative trichologist to the Institute of Trichologists, let us in on a few secrets...

1. You don't need to wash your hair as often as you think

No doubt some of your friends insist on washing their hair every day, whereas others can get by with just once a week. Which end of the spectrum is right? Well, there's no general rule, as everyone's hair is different.

Stephen says: "Those with fine, oily hair will need to wash around three to five times a week. Those with normal hair that feels slightly oily after four to five days should aim to wash around then, and people with dry scalps should shampoo every six to seven days."

Lisa agrees with Stephen, saying the frequency depends on your scalp type and how much physical activity you do.

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2. Environmental factors and how much you exercise make a difference

Everything from where you live to the shampoo you use can affect how often you should wash your hair.

Stephen notes you need to be particularly careful when choosing your products. He says: "For example, moisturising shampoo will not have enough cleansing properties for oily hair, which will make the hair lank and need washing more often.

"If you live and work in a city centre, pollution, dust and grime will mean your hair needs washing more than if you live in an area of cleaner air." And as any regular gym-goers know, frequent exercise also means that you need to wash your hair more often.

3. No, hair can't 'wash itself' if you leave it long enough

Ah yes, the age old myth that if you just don't wash your hair, it'll start 'self-cleaning'. It's a tale that most wish is true, but few have actually been brave enough to test out. Well, now the professionals have spoken.

Lisa says that you shouldn't waste your time hoping your hair will eventually self clean, because it's not going to happen any time soon. "Sebum is the skin's antibacterial layer and has no cleansing properties in," she says. "It can be unhygienic."

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4. Washing too often dries it out and makes coloured hair fade

Washing your hair too regularly runs the risk of drying it out, especially if you don't use conditioner. Stephen says: "You may also find your scalp getting dryer and possibly itchy."

You need to be particularly wary of this if you've had it coloured or put other chemicals in your hair, as it will dry out more quickly.

Lisa adds that using shampoo which doesn't strip out the natural oils, along with limiting how much heat is applied to the hair when styling, can help us all have healthy locks.

5. Pat hair dry instead of rubbing it with a towel

Washing hair is such a dull part of your life, you probably don't spare it second thought. However, this means that many people go on autopilot and therefore make some basic errors in their regular routine.

Lisa says: "Women often use the wrong shampoo for their hair type, apply conditioner to the scalp, and rub the hair with the towel as opposed to patting it dry - this can charge the hair electrostatically, making it flyaway."

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6. Showering in water that's too hot is a mistake

For Stephen, there are a whole host of simple mistakes we make when washing our hair.

He says: "Common errors include using water that's too hot, which has a drying effect on the scalp, not rinsing hair thoroughly enough (which can cause a dull appearance due to debris left on the cuticle), and rubbing the hair too vigorously with a towel afterwards."

Instead, avoid damaging the cuticle by blotting your hair gently dry.

7. Brush your hair before washing it

If you've got long hair, remember to brush it first. Also, most of us tend to lather up all of our hair on top of our head like a shampoo crown.

Stephen says: "Instead, keep the foam close to the roots and then let the lather run through the hair as you rinse."