Vincent Deary is a clinical and academic specialist in fatigue, in the ways in which we might be mentally and physically spent by life. This book, part memoir of his working practice, part inquiry into the ways in which mental health is undone, is a sequel to an earlier volume, How We Are, published in 2015. The chronology is pertinent. The trajectory of those intervening nine years of austerity, and pandemic, and precarity, serve to make this volume both inevitable and urgent. Sleeplessness and anxiety have been among the few growth sectors in that decade. If Deary’s previous book was, just about, a meditation on how we might thrive in the world, this one is a subtle catalogue of the ways in which we fail to do so. One of his colleagues has a phrase for our prevailing psychological moment: “It’s like we are always one step ahead of the hounds.”

There is a rawness to Deary’s analysis that gives a compelling human edge to his theorising. Some of that comes from his allusions to a breakdown he himself suffered in recent years. Otherwise, he dwells on case studies of people he has met in his work, individuals whose “allostatic load” of stresses – the camel’s-back-of-straws waiting for one too many – become overwhelming. Some of these case studies are composites of patients, juggling jobs and debts and caring responsibilities and trauma and regret; two significant stories he returns to are those of his mother, Isobelle, a force of life in the world who descended in her final years into the blackest of depressions, and of his former partner, here called Sami, an NHS nurse, who has overcome sexual abuse in his childhood only to be unravelled by the uncertain shift patterns and unfair bureaucracies of his job. (Having been up all night with one psychiatric patient on suicide watch, Sami cracks when reprimanded for drinking a mug of coffee in a staff room to which he is ineligible.)

It is the book’s persuasive contention that we are “born trembling” in one way or another, three or 23 reversals away from breaking after our own particular fashion, more or less temperamentally at odds with where we fall to earth. Deary’s mother, a creative and volatile spirit, became a mother in working-class Scotland aged 19 to escape the “fools in old-style hats and coats” who had constricted her own childhood, and found herself in a different kind of compromise. She characterised that struggle in a favourite phrase, an inversion of the usual platitude: “What doesn’t kill you makes you scunnered.”

With the aim of avoiding being “scunnered” – bitter, hopeless – Deary punctuates his book with a series of health checks: “How precarious are you, in your labour, in your home life, in yourself?” In doing so he makes a powerful argument against some of the contemporary factors that undermine security: the “audit culture” of the world of work that seeks to constantly measure our performance against nebulous targets; the shift in focus in the welfare state away from a culture of care toward homilies about “resilience”; the erosion of healthy perspective in the “ambient hum” of social media; and the fact that, as a society, “we have lost the knack of convalescence”, the space and capacity for deep rest that might accelerate recovery.

Deary is clearly an eclectic reader and his studies have him reaching as often for quotations from Terry Pratchett and George Eliot as from the Diagnostic and Statistical Manual of Mental Disorders. He describes the “way that events and exposures get folded into our body, heart and mind” as being “still an emerging field of research” but, of course, that science of internal commentary has been the territory of the greatest novelists for at least a couple of centuries. Reading this book had me re-reaching for F Scott Fitzgerald’s seminal essays on his own “crack-up”, not least because the speculative cadences of some of Deary’s metaphors are reminiscent of those pieces; Fitzgerald was a reluctant connoisseur of allostatic loads: “In a real dark night of the soul it is always three o’clock in the morning, day after day.”

At the heart of Deary’s analysis – as with Fitzgerald’s – is the idea of our minds as storytelling machines, which go haywire in “our periods of trembling and breaking”, feeding us delusion and addiction and compulsion and paranoia. The second half of his book is devoted to the strategies that might protect us from those rogue internal narratives. In particular here “the third wave” of Cognitive Behavioural Therapy, known as “acceptance and commitment therapy”, a process that begins with the notion that your mind – at essence “more of a problem finder than a problem solver” – is not always your friend. The self-help wisdom here is properly caveated and hard-won, but there is still enough for the odd inspirational Post-it note. Here’s one: “The work of wellbeing is not to change the play but to be the theatre… hold your self-stories lightly and be lightly held by them.” Happy new year.

• How We Break: Navigating the Wear and Tear of Living by Vincent Deary is published by Allen Lane (£25). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply