Would you go days without washing your face or your armpits? What about your hair? If you could go days (weeks even) without having to give it a spruce, would you? Could you?

When it comes to our scalps, we don’t think of it in the same way as the rest of our skin. And while our hair is dead (beyond the roots, at least), our scalp is effectively an extension of the skin on our face. It accumulates bacteria, has follicles that can become blocked and even sweats like the rest of our skin. “Like the skin elsewhere it can become clogged and dull,” explains top hairdresser Michael Van Clarke.

Dry shampoo – wondrous though it is – has contributed to waning scalp standards. We wouldn’t paste over sweaty armpits with deodorant for three or four days on the trot without washing them. But the dry styling spray has enabled us to eke out extra days without cleaning our hair (and by extension, our scalp), which effectively provides it with extra days to accumulate bacteria. A little oil is good, helpful even – “when balanced, sebum can help the hair look soft and shiny,” says Michael. But too much can be tricky. “A build-up of sebum on the scalp can clog the pores and feed the bacteria that leads to dandruff. It can also trigger seborrheic dermatitis which creates angry red patches, itching and flakiness,” he says.

But even those of us who clean our scalps as regularly as recommended may be getting it wrong. Overly harsh shampoos and styling products can add to the problem. “Often not designed for skin, these products seep down, build up and easily clog the hair follicles,” says Michael. Over time, “it can lead to some chronic scalp and hair conditions,” he warns, and in more extreme cases can contribute to thinning hair.

So what’s the answer? For starters, it’s worth looking for gentle, scalp-friendly shampoos. If you find your scalp is sensitive, it might be worth avoiding sulphates like SLS which contain a strong detergent. Even better, look for shampoos that offer up skincare benefits – these can be the same as what you’d find in your facial skincare. Camellia oil is one such example. “It’s been used as a traditional hair and scalp treatment since ancient times in Asia, delivering conditioning and moisturisation,” explains Peter Bailey, who heads up Unilever’s Research and Development team. As such, it can help to keep your scalp hydrated and supple. “Plus, it has antioxidant properties, which neutralise free radicals to help keep the skin on your scalp healthy and strong.” As for your hair itself, it can smooth down cuticles and add shine. Others to look out for are aloe vera, charcoal, kelp and olive oil.