There is hardly a shortage of books about depression. Far from being the illness that dare not speak its name, it is actually quite hard to get it to shut up. William Styron's Darkness Visible, Lewis Wolpert on his Malignant Sadness, Elizabeth Wurtzel's citizenship of Prozac Nation are just the stand-out titles in a crowded if somewhat subdued genre. And that's before you start casting back through bits of the Iliad, most of Hamlet and all of Burton's Anatomy of Melancholy.

It is, though, in the nature of depression that the sufferer believes that no one has ever felt quite like this before, that there is nothing to read that quite matches up to their own experience. It's for this reason that Mark Rice-Oxley decided to write a book about his own experience of what, in an earlier age, might have been called a nervous breakdown. Under the Lemon Tree could be subtitled "ordinary bloke goes nearly mad in middle age". Rice-Oxley (pictured) was a dad of three with a good marriage and an interesting job as a news editor on this paper when he started to feel peculiar. So peculiar, in fact, that on a Thames river boat party to celebrate his 40th he begged his mother to stand as close to him as she did on his first day at school. If she strayed out of his eyeline for a moment, there was no telling what might happen next.

As these peculiar feelings dig in over the following weeks, Rice-Oxley finds himself sitting on the floor of his three-year-old daughter's bedroom, unable to complete one of her ABC puzzles. And this is where his book is particularly strong, on the way the physical world warps as you sink deeper into depression: station platforms seem like death traps, walls rear up from nowhere and everyday objects slip through your fat, stupid fingers. And then there's the cold ringing in your ears and the wavy lines in front of your eyes that make everything look like a knock-off Picasso. All of which is made worse by the sort of bone-tiredness that comes from never getting more than a few hours' sleep at a time. Rice-Oxley catches exactly the persecution of pre-dawn wakefulness, that jittery alertness that can be assuaged only by taking a pill that plunges you into a thick coma from which you struggle to emerge, as if swimming up from the bottom of the sea.

Slightly less persuasive is his attempt to stitch his particular experience into a broader inquiry about what depression is, where it comes from and where  if you're lucky  it eventually goes. He starts with an account of his childhood, which sounds picture-book perfect, although a psychoanalytically inclined therapist might want to press a bit harder on all those sunshiny memories of rural Hampshire in the 1970s. Rice-Oxley then  for reasons that aren't quite clear  gives us episodes from his time as a freelancer in eastern Europe during the chaotic early days of perestroika. At one point when he is in the depths of darkness someone helpfully suggests that perhaps it is the "terrible things" that he witnessed in Bosnia in the 1990s that lie at the heart of his present despair. But he has to admit that he hasn't seen any. In fact, he has always worked hard at making sure that he stays safe, a working practice that usually results in "half a story but all of my life". Which in turn, of course, only engenders an extra feeling of bogusness: here is a man who has no reason not to be counting his lucky stars.

But maybe not entirely. Where Rice-Oxley gets close to a workable explanation for his sudden unravelling is in his description of what life is like for a modern middle-class man. Committed to being an involved parent, loving husband and competent professional, he stretches himself to transparency. His schedule sounds dizzying, a frantic programme of night shifts, school runs, and shopping in bulk. And then, because he's a bit of a perfectionist and deeply competitive too, there's also the intensive physical training, the 15-mile cycle ride home from work. In short, Rice-Oxley suggests, he is suffering from the sort of "having it all" culture that sends working mothers into a slither, but to which men have always been assumed to be bullishly immune.

It's complicated, though. Rice-Oxley's father turns out to have had a period of depression in middle age, so maybe it's genetic. And, since Rice-Oxley's own malady came on in the winter, he also thinks that there might be a seasonal element, and starts to map his despair against the dying of the sun. Then there's the whole serotonin thing  the thesis that depression is the result of the brain's neurotransmitters being out of whack. Certainly anti-depressants seem to work like a charm for many. But then Rice-Oxley talks to a prof at Cardiff University who makes a brisk case for Prozac's popularity being all about the placebo effect. (Someone suffering from depression wouldn't really mind about this last bit, though: if it works it works.)

Running through this inquiry into the causes of his collapse, which meant taking six months off work, is the story of Rice-Oxley's treatment. The help he gets is a lurching mixture of NHS and private and seems to involve a blend of psychiatry, psychotherapy and a fair dollop of self-help in the form of yoga and meditation. There's a big shout-out for mindfulness therapy, a soulful gloss on the more standard cognitive-behavioural approach, which is beginning to find a promising take-up in various bits of the country. But which of these approaches, or in what combination, begins to push Rice-Oxley towards wellness is not clear, and perhaps never can be.

Kathryn Hughes's biography of Mrs Beeton is published by Harper Perennial.