ohOne thing after another happened, and I was lying shirtless on the couch, with a wrinkled nose as a cardiologist explained that everything was fine, but that my heart was a little… weird. I can’t remember the exact words, but it was probably just above “quirky,” but not quite weird. He was looking at something else entirely, and had noticed that the valves at the top of my heart were a little weird. It had absolutely nothing to do with why I’d come here, and was unlikely to affect my future health in any way, he said. But now that he’d seen it, he thought it best to tell me. I asked if it was good to know, and he shrugged. “Sometimes?” he said vaguely. “It’s complicated.”

At home, I paid more attention than usual to my heartbeat, listening for any unusual sounds. A few months later, when I experienced what turned out to be indigestion, I went to the doctor, worried that my valve was about to burst. I had no history of anxiety disorders and had never paid much attention to what was going on inside my body, thinking it was inevitably unfathomable, like anything going on in the vast depths of the ocean. But once this flaw was revealed, I became uncomfortably aware of every moving part, of everything that might go wrong.

When I read Caroline Crampton’s recent detailed study of hypochondria, A body made of glass aptly describes health anxiety disorder as “a bodily illness that exists only in the mind,” and my hand immediately went to my chest. From 18th-century quack medicine to today’s health industry, Crampton traces the rise of drugs and devices promising relief from imagined ailments, such as the Zeebo pill (currently £73 on Amazon), which is promoted as a placebo and “you yourself are the active ingredient,” and plans for technology that can observe every part of our minds and bodies. But, she asks, can we ever know too much? Reading recent criticisms of blood glucose monitoring and the rise of the Zoe app, I thought of Crampton’s book. These are part of a growing trend for personalized diets, but along with other criticisms (such as a lack of evidence about their effectiveness), Professor Partha Carr, the NHS’s national diabetes adviser, told the BBC that using a continuous glucose monitor (designed for diabetics) for no health reason can make people obsessed with the numbers and, in some cases, “can lead to eating disorders.”

These are apps for “worried people” – healthy people who worry about their health – a growing market at a time when new technology and the old internet are stoking anxiety by providing vast amounts of knowledge to anyone with Wi-Fi. It’s a successful business model, in that they’re both apps for anxious people and apps that create anxious people. Parents are especially susceptible to marketing, with health anxieties projected onto their children. This month’s New YorkerJia Tolentino detailed her efforts to hide her pregnancy from her phone, which meant not buying baby clothes online, not using a period tracker, and not using pregnancy apps. She wanted to avoid being watched, which can be especially hard when you’re encouraged to watch yourself.

In the time it took me to give birth to my two children, there had been an explosion in the technology offered to parents who wanted to both track their pregnancies (through additional ultrasound scans, for example) and keep an eye on their babies (with devices like stuffed toys with hidden cameras or disks that attach to diapers that alert you when your baby rolls over). By 2020, I was surprised at how hard it was to buy, for example, a baby monitor that didn’t include a camera, didn’t require a Wi-Fi connection, and didn’t capture any data. And yet, despite the desire for parenting technology, Tolentino found that it rarely led to better outcomes for babies, but rather exacerbated or, worse, created the anxieties that led to the purchase of these devices. The control that anxious people seek by monitoring their babies and their bodies is an illusion.

This is disturbing, given the growing number of products targeted directly at them. The global wearable technology market (fitness trackers and other devices) is expected to be valued at $61.3 billion in 2022, and to expand significantly by 2030. My 9-year-old’s school friends regularly compare FitBits. But for some, trackers and the like may be doing more harm than good. New Statesman In 2019, a professor of cardiovascular medicine criticized a large study of atrial fibrillation (a common heart rhythm problem) in Apple Watch owners, saying there was no significant health benefit to testing low-risk people, “the kind of people who wear Apple Watches,” and that the study would “inflict substantial distress” on healthy people who would receive notifications about their irregular heartbeat.

Health anxieties have evolved alongside scientific knowledge, with phrases like “cyberchondria” (anxiety heightened by information found online) emerging and some research suggesting that our new loose connection to medical knowledge is making people more anxious rather than lessening it. I resent the way tech companies prey on these anxieties, creating new concerns for profit. I believe it’s true that we can know too much.

Every now and then, a small pain or memory in my chest will raise a chill and I’ll think about my deformed heart, but in those moments I will tell myself sternly that it’s none of my business what’s going on under the sea, or deep inside my body (as long as it doesn’t affect my life).

Email Eva at e.wiseman@observer.co.uk or follow her on X. Eva Wise man