Something is happening in the Young Adult market.

Perhaps it's coming of age, finding its feet, playing with its self-image, and doing so at a time when, though adult book sales are dwindling, the sector's sales are, according to recent figures, rising. Earlier this year, the first ever YA Book prize was awarded to Louise O'Neill for her dystopian, feminist satire, Only Ever Yours, an event that seemed to mark the sector as something to be taken seriously.

But actually what's notable, in spite of O'Neill's win, is that YA appears to be moving away from the fantasy and other worldliness that seems to have dominated it. Realism is gradually ousting the vampires and warriors that were once was dominant, as heroes and heroines go up against their own demons or those of the society around them. Pregnancy, depression, illness, the journey of finding and expressing one's own sexuality: this is the stuff of today's YA.

One of the standout trends this year is for books exploring gender and sexual orientation. When I first started writing these reviews one teenager complained to me that there few books with gay or lesbian characters. In 2015, however, a swathe of LGBTi novels are coming out: books like None Of The Above by IW Gregorio, the story of a girl who discovers she was born intersex, and Simon Vs The Homo Sapiens Agenda by Becky Albertalli, about a young gay man coming out.

There's also Liz Kessler's Read Me Like A Book (Orion, £10.99), a novel which, notably, Kessler started 15 years ago during the era of Section 28, at a time when it was illegal to promote sexuality in schools and so such books were, effectively, banned. It's the story of Ashleigh, a sixth-former who is surprised to find she has intense feelings about her English teacher, Miss Murray. When she winks, her stomach does a backflip. "Shouldn't I have felt like this," she ponders, "about my boyfriends rather than Miss Murray?" Simply told, it's also an utterly involving and moving tale of a young woman getting to grips with her sexuality, as she struggles with other teenage and personal issues: the break-up of her parents' marriage, a fall-out with a friend, a pregnancy scare. Tissues required.

I'll Give You The Sun by Jandy Nelson (Walker, £7.99) features a young gay man dealing with his feelings, though it's in no way the most remarkable thing about this book: rather, it's just one of the wild and vivid brushstrokes in a dazzling portrait of two lives of the searing bright passions and torments of youth. Noah and Jude, non-identical male and female twins, have an almost telepathic bond, but then a tragic accident severs them, leaving them both transformed, barely semblances of their former selves, one steeling herself against all possible relationships, the other cut off from the painting he loves and bent on self-destruction. It's about love, but it dispenses with all the tired conventions of teen romance: Jude, hurt and racked with guilt, is doing her best not to fall for anyone. This is young adult realism in Technicolor, saturated with light and punctuated with darkness. Like John Green, Nelson is producing the kind of YA books, you don't have to be young to read (one study found that 55% of YA books were bought by people aged 18 or older, and many by those in their thirties).

David Owen's Panther (Constable & Robinson, £7.99) is an extraordinary and gripping examination of the impact of depression on a whole family. One of the most impressive things about this textured and sensitive debut novel is that it takes us inside the world of the kind of character rarely seen in teen or adult fiction. Derrick weighs 18 stone and seeks out junk food to soothe his anger and pain as he tries to cope with the fall-out from his sister Charlotte's depression and recent attempted suicide, as well as the bullying he experiences at school. "He ate because everything at home was out of control. He ate because it made him feel in control." But food is not his only coping mechanism. As it happens, there are news reports that a black panther is on the loose in his area, and he fixates on trying to find The Beast. Rather like Roddy Doyle's Brilliant, which featured a group of children trying to hunt down The Black Dog, it gives animal shape and form to the mental illness that plagues Derrick's family, and that has "closed them off from the rest of the world".

But realism isn't always about hard stuff and big issues. There are also some rather wonderful books that simply feature vivid, engaging and complex young adults. Steven Camden, the oral poet also known as Polarbear, follows up his debut, Taped, with It's About Love (Harper Collins, £7.99), the story of Luke and Leia, two film students whose lives are rather authentically and wittily saturated in pop culture.

Lisa Heathfield's Seed (Electric Monkey, £7.99) doesn't read like realism, though it plays out in contemporary England. This atmospheric debut novel, the first of a two-part series, has a dystopian feel mainly because it's set in a small cult, Seed, that worships Mother Nature and has attempted to isolate itself from the outside. The start is arresting: a visceral description of the central female protagonist's first menstruation, an event that leaves her confused and panicked because the community is so cut off. But it's the gentle pace and building up of the at times idyllic, yet also sinister, world of Seed that beguiles. Three outsiders come to live at Seed, and everything begins to unravel, slowly and sometimes predictably, though always compellingly.

All this is not to say that fantasy has entirely vanished from YA. The big names are still turning out books which are immediately gobbled up by an ever hungry fanbase. Sarah J Maas, whose Throne Of Glass series, inspired by Cinderella, was a bestseller, is back with the first in a new trilogy, Court Of Thorns And Roses (Bloomsbury, £7.99), a twist on the Beauty and the Beast tale, with a bit of the Borders ballad Tamlin thrown in and some hot "swoony guys" as some fans call them. I didn't warm immediately to this book, though the world Maas has created, with its shape-shifting fae and dark surreality, is entirely enthralling, and her heroine, Feyre - a young woman struggling to keep her father and two sisters, a selfish and useless bunch, from starvation by hunting wild beasts - is one of those embattled warriors one can't fail to root for. The problem, in part, is her choice of tale, Beauty and the Beast, and its themes of imprisonment and control which often appear abusive and which give the whole thing a slightly Fifty Shades feel.

That said, I am a lover of contemporary stories that use folk tales as a springboard to create something marvellous, and that is to be found in Joan Lennon's Silver Skin (Birlinn, £6.99), published by Birlinn's new children's imprint. An entrancing channelling of selkie mythology through sci-fi, it follows Rab, a future boy growing up long after an environmental catastrophe, in a technologically advanced world where sexual appetites are repressed, pain is immediately anaesthetised and people play a lot of virtual games. Rab puts on a skin - not a seal skin, but a specially designed time-travel Silver Skin - and attempts to go back to Orkney in the 1860s. Shot down by lightning, though, he ends up tumbling to Earth at the end of the Stone Age, where he washes up on the shore of Skara Brae, his Skin on fire, and looking, to the locals, every bit like some magical creature of the sea: a selkie. A local girl, Cait, and the island's wise woman, Voy, look after him as he recovers from his burns.

It's a beautiful and mesmeric tale, rising and falling between its different narrators, sometimes as if drifting in and out of sleep. But it's also an examination of our relationship with the environment and catastrophe. One character ponders, "The times have never been so cruel - can you remember, ever? - not ever. They say the Sun is fading. Dying. What have we done? What can we do?"