In your spa time

It's all about you. From the second you check in, you're on a journey to your New Self, cast adrift from the everyday world on a magical island filled with repetitive tinkly-bell music and herbal teas. Before so much as a drop of hot oil has been poured, you know you're going to leave a better person. Well, maybe.

Spas, those seductive environments dedicated to narcissism, are a muddle. What they sell is a mish-mash of promises—better health, better looks, an enhanced sense of wellbeing—using at one moment what they describe as all-natural, all-organic products, the next hi-tech, sub-medical procedures. They globe-trot for their philosophies, grabbing a bit of Swedish massage here, a Balinese hot stone there. And the claims made for many of their procedures are vague and hard to prove: it's all very well recommending a monthly facial for "optimum skin maintenance", but what difference, exactly, does that "maintenance" make?

A muddle, then. But a very successful one. Between 1999 and 2010, America saw its number of spas rise from 4,140 to 19,900. The British spa industry continues to steam past the more traditional end of the beauty market, such as hairdressers. And despite a 15% loss of revenue immediately after the crash of 2008, spa tourism—holidaying for your treatments—is one of the world's largest leisure industries; in just two years, Dubai has seen a 66% increase in day spas catering to holiday-makers. Why is arguable. Some within the industry say it's because they offer services that are hard to replicate at home; others because there's a continuing increase in the numbers of working women. What is clear is that, in Britain at least, the industry is largely supported by young urban women and, increasingly, young men.

So will any of this do you any good? It rather depends. Only a handful of chains claim to train their staff. Elsewhere you might find yourself in the hands of an 18-year-old living in fantasy land; I was once told by a young masseuse that she needed to "pull my toes" to "release the gas trapped in the joints". Few spas run to qualified doctors, so clinically proven medical treatments are thin on the ground. (And in many American states, even in a licensed "medi-spa" a doctor doesn't have to be present during treatments.) Meanwhile, a study from 2004 found that hydrotherapy—a popular offer at many European spas—had no added benefits over and above those of ordinary, land-based exercise for sufferers of arthritis or chronic back pain.

There are a few pluses. Losing weight, which some spas will help you do, is a health benefit—as long as you are overweight to begin with, don't lose weight too fast, and keep it off afterwards. Auberon Waugh, the late columnist and son of Evelyn, holidayed annually at spas—but only, he said, so that he could eat and drink without compunction the rest of the time. And then there is the power of human touch. Facials will make your skin glow—for a little bit, because all that rubbing and patting encourages surface blood flow. In 2008, psychologists in America found that gentle, caring touch lowers blood pressure and encourages the release of the "cuddle hormone" oxytocin. So even an amateurish massage is soothing, as long as the whale music doesn't drive you insane.

Perhaps the best way to look at spas is as a slightly silly, but—if done well—very relaxing treat. With that in mind, the ESPA spa at One & Only in the Maldives is worth recommending: purpose-built in its own pavilion, it feels like a truly private world and not some tacky afterthought. In Amsterdam, Sauna Deco offers a steam room and proper, pummelling massage in an Art Deco building full of stained glass and carelessly naked Dutch people. And of the beauty-centric international chains, Bliss day spas have well-trained therapists and an attractively American belief in the customer always being right. As we said, a good spa should always be about you.

ILLUSTRATION RICHARD ROCKWOOD