One of my maxims as a university teacher of literature was: “A great novel not only enhances our understanding – more crucially it understands us.” When I later trained as a psychoanalyst I annoyed my tutors with my refrain that one could learn more about the subtleties of human psychology from literature than from the works of Freud, Adler or Jung. This was not to decry the pioneering wisdoms of those great psychologists, but years of teaching literature convinced me that fiction trumps theory in its illumination of the hidden recesses of our consciousness.

There is now good evidence for the therapeutic effects of reading. The Shared Reading project, organised by the Reader Organisation, suggests that reading in groups – in their case they bring together groups of people with mental health issues for example, but the findings apply as well to the local book club’s monthly gathering with added wine – significantly “improves self-confidence and self-esteem, builds social networks, widens horizons and gives people a sense of belonging, preserving the mental and physical health of those who are well and building mental resilience”.

Chronic loneliness and isolation are now prevailing social problems, but it is not necessary to be part of a group reading project for a book to have a role in ameliorating this social malaise. As the shrewd and alienated Holden Caulfield says in JD Salinger’s The Catcher in the Rye: “What really knocks me out is a book that, when you’re all done reading it, you wish the author that wrote it was a terrific friend of yours and you could call him up on the phone whenever you felt like it.” I think many of us can count some books as close friends (my particular friends are Henry James’s The Portrait of a Lady and Patrick White’s Riders in the Chariot). And it is by no means a trivial good that, at a fundamental level, reading confers a benefit by entertaining us. To “entertain” means to “admit, cherish, receive as a guest” and books can, and do, dissolve social isolation, as the estranged and damaged Caulfield exemplifies, by inviting in the reader to become involved in an imaginal world. Immersion in a fictional society seems to promote many of the rewards of immersion in actual society: among other benefits, it encourages escape from the self, by no means always escapist. To get outside the confines of our individual egos is a liberating experience, and entry into another universe, by way of the written word, may be a safer, or more practically possible, route for some – for the elderly, the incarcerated or the emotionally fragile, for instance – than by personal physical encounter. Among the Shared Reading successes is its work in psychiatric hospitals and prisons.

‘Each unhappy family is unhappy in its own way’ … a scene from the 2012 film adaptation of Anna Karenina. Photograph: Focus Features.

I suspect what is most fruitful about the encounter with a literary landscape is the intimate knowledge it encourages of other human beings, albeit fictional ones, often surprisingly like ourselves. It is here that the “understanding” granted by great literature becomes therapeutic. The opening pronouncement of Tolstoy’s Anna Karenina, “All happy families are alike; each unhappy family is unhappy in its own way” applies to more than families. All unhappy individuals are unhappy in their own way, too. This is partly because self revelation is far from easy and self understanding, and the vocabulary for it, is rare. But it can often be apprehended helpfully in the accounts of fictional sensibilities.

Take Charlotte Brontë’s Villette, for example (a novel which, in my view, surpasses the more celebrated Jane Eyre). Its hero, the emotionally repressed Lucy Snowe – plain, lonely, angry and desperately striving to be self-sufficient – suffers a painful breakdown as a result of weeks of friendless solitariness during her time as an English teacher in a Belgian school. From my professional knowledge of breakdowns, Brontë’s account is pin-sharp accurate and not only conveys a depth of experience (whether actual or imaginative) in its author, but acts as an objective correlative for those who have suffered in similar silence, conferring a critical lifeline, in the sense of not being quite alone in the world. Similarly, anyone who has undergone the wounding experience of family discord and alienation will find resonances in King Lear or Marilynne Robinson’s Home.

Perhaps more surprisingly, and more radically, we may discover in a book shadow aspects of ourselves we have failed to acknowledge or recognise. Few of us imagine we are potential murderers: yet few reading Crime and Punishment can fail to enter the tortured consciousness of Raskolnikov, who believes in committing a murder he is acting justifiably, or fail to empathise with his anguished punishment of guilt. Dostoevsky illuminates, through the example of his character, what we might otherwise be too defended to comprehend: that our civilised selves may conceal a lethal armoury, potentially capable of atrocities, and that those who justify killing in the name of ideology are not as alien as we might care to believe.

Exploring dark psychology … the film adaptation of Lolita. Photograph: Ronald Grant Archive/Ronald Grant archive

So reading is not merely a diversion or distraction from present pain; it is also an enlarging of our universe, our sympathies, wisdom and experience. The act of entering into the consciousness of another being, another sex, or sexual preference, social group, political outlook or religious persuasion, allows a respite from private and parochial preoccupations. That widening of our concerns may entail entering another location, or period in history – or an arena of which we would otherwise be ignorant. Education, as people are never tired of repeating, is a process of leading out, which suggests another benefit: that in being led by reading into previously unknown territory, we learn.

• Salley Vickers’ latest novel Cousins is published by Viking.