Christmas Eve, 1999. I was a mere 24 years old. I was standing in my parents’ kitchen in Newark-on-Trent, helping them prepare for the small party they always held after the local Christingle service. My mum and my girlfriend chatted as they made mulled wine. I chopped vegetables and stared at the knife, imagining what harm I could do to myself.

I had been recovering slowly from the breakdown that had taken hold of me violently a few months before, an intense anxiety and depression that had nearly caused me to jump off a cliff in Ibiza and had turned simple decisions, such as choosing which socks to wear, into existential crises. I had been getting a little better, because all the ridiculously melodramatic things depression had screamed at me continually (“YOU’LL BE DEAD IN A MONTH!”, “YOU’LL END UP IN A PADDED CELL!”, “THE WORLD WILL END!”) hadn’t happened. The one thing bigger than depression is time, and I got through days the way other people counted money.

That November, I had been able – just – to walk into town on my own without always having a panic attack. But in the days before the party I had been feeling very ill again. Christmas was part of that, which confused me. I wasn’t a natural Scrooge. I had always enjoyed Christmas, more than most other times of the year, and I had always seen it as a chance to escape the pressures of school or university by diving in to a world of magic and movies and mulled wine.

Back in the kitchen in 1999, my mum realised she needed more ingredients. I volunteered to go and get them. The corner shop was closed, so I needed to head to the nearest supermarket – a Morrisons on the edge of town.

“Will you be OK?” my girlfriend asked me.

“Yeah. ’Course.”

“I can come with you.”

“No, no. I’ll be fine.”

I can remember the horror of that Christmas Eve walk. There was terror everywhere. Christmas lights shone with sinister menace. Laughter flapped out of drunken people like bats from a cave. The wind was cold and sharp and loud in my ears. The faces I passed seemed so happy they must have belonged to another world – or maybe I did. My body was leaden with dread and fear when I knew I should be happy. In Morrisons, I had a panic attack to the tormenting sounds of Slade and Cliff Richard.

Christmas, I realised, could be a nightmare. It could intensify what depression already, to some extent, made you feel: that the world was having fun while you definitely weren’t. Christmas intensifies the chiaroscuro (to use the pretentious kind of art-history terms I had in my head at the time): the contrast between light and shade. The light around you seems brighter, so the dark feels darker.

I should have known that the idea of Christmas as one of collective happiness wasn’t the case. Indeed, the first time I heard about suicide was when, back in the 80s, one of my parents’ friends hanged himself on Christmas Day.

Relationship stress and financial worries are classic triggers of depression, so it’s no surprise that Christmas can be an agonising time. Add an excess of alcohol, 4,000 calories above doctors’ daily guidelines and the likelihood of hearing some of the most catastrophically annoying music committed to record and you have a recipe for psychological trouble.

But there’s something else at work. Christmas is one of those times when the idea of something doesn’t match the reality. As a result, we can easily fall in to the gap between how we think we should feel and how we actually feel. We imagine that everyone else is having a great time – everyone but us. This may be because we are alone in what feels like a world full of family gatherings, or because we are surrounded by our loved ones – at least, related ones – but don’t feel the happiness we think we should.

Depression often occurs when it looks like we have reasons to be happy. Postnatal depression can be exacerbated by the expectation that a baby will bring happiness and that there’s something wrong with you if you don’t – can’t – feel this happiness because of your illness. (Let’s remember: depression is an illness, one that happens to you, not because of you.) Christmas – or birthdays, or weddings, or sunshine, or celebrations, or lottery wins, or fame – can work in the same way. The knowledge that something should make us happy forces us to think about happiness – and how much we lack it.

So, how can our fragile minds insulate themselves against Christmas? You could try to ignore it, but good luck with that. You may as well try to ignore time itself. And, as with any mental health issue, denial is not a good strategy. You need to look the thing in the eye – whether that thing is a panic attack or Boxing Day with the in-laws (or a bit of both). For instance, the best way to beat a panic attack isn’t to run away from the panic attack; this only heightens the panic and makes you panic about panicking. Similarly, while depression is unavoidable for some people, getting depressed about being depressed is something we can work on. A massive part of my recovery was accepting that I was depressed, or that I was the type of person who could get depressed, and being OK with that.

In fact, I learned to get over depression – partially – by being thankful for it. Yes, it made me thinner-skinned, but, when I was better, my thinner skin made me feel the good stuff of life – love, art, music – far more intensely than ever before. In other words, the key to getting over depression often lies in depression itself. Maybe the key to coping with Christmas is to head towards it, rather than to run away. Maybe the answer to being happy – or less miserable – lies within Christmas. Perhaps when we look at Christmas more closely – and I mean the secular, pop-cultural idea of Christmas – we might see things a little differently.

In It’s a Wonderful Life, the ultimate Christmas staple, George Bailey is so depressed at having sacrificed his dreams and ambitions that he plans to kill himself on Christmas Eve. However, a guardian angel appears and shows George that the only thing wrong with his life is his perspective on it. Yes, sure, his decisions stopped him becoming rich, and a bad ear stopped him becoming a war hero like his younger brother, but he made all manner of differences to the lives of others. He helped people in many unrecognised ways. His life had mattered. It’s a film about seeing the glass half full, a kind of cinematic CBT that makes us feel – like George – that our humdrum lives are full of the magic that we think is missing. It’s no coincidence that the film is set over Christmas, when our potential for soaring highs and crashing lows is at its peak.

I suppose, in 1999, I felt a bit like George Bailey. My wiring, and my perspective, was all wrong. I felt like a total failure. I was back living with my parents. I was depressed, broke, suicidal and panic-swamped, and I was made more anxious by all the things Christmas seemed to represent: shopping (there is nothing like a patch of depression to make you realise that shops are not good for our minds), enforced jollity, noise, wine, parties, laughter, the tyranny of merriment.

Many of us have some of our best childhood memories wrapped up in the buzz of late December, so Christmas can feel like a funeral for our happier, younger selves. In 1999, and for a few years after, I was convinced I would never be able to enjoy Christmas again. But, back then, I was convinced I would never enjoy life again. I was also convinced I wouldn’t live to see 25, but I turned 40 this year. Depression lies.

We should put Christmas depression in perspective. Contrary to popular belief, the Christmas holiday doesn’t bring a marked increase in the number of suicides. In fact, January offers the bleakest picture in terms of suicide and new prescriptions for antidepressants. You could say that the end of Christmas is more depressing than Christmas itself.

What is Christmas, anyway? A combination of Christian, pagan, secular, Dickensian, John Lewisian and capitalist traditions, it’s big enough to be whatever you want it to be. I choose to see it as a stand against the cold and dark of winter. Like the winter solstice festivals that pre-date it, Christmas is about light and warmth and togetherness in the face of bitter cold. It’s a break from the weekly grind, a way of putting more life in the work-life balance.

One reason many of us find Christmas hard in the 21st century is the fact we have to spend time with people we don’t like. Social media allows us to edit out people with whom we have nothing in common, but Christmas often forces us to do the opposite.

In a way, though, Christmas is more valuable today precisely because of this. Sitting down on Boxing Day with your mildly obnoxious, rightwing relatives can be an exercise in empathy and kindness – and kindness is therapeutic. It takes us out of ourselves. “I will honour Christmas in my heart,” said Scrooge, “and try to keep it all the year.”

Christmas can get to us, sure. But it can also help us. If we edit out all the noise, we can close our eyes and remember a time when we believed in magic and miracles. When I was 24, and ill, Christmas had lost all its magic, because I had stopped believing in impossible things. Now, I’m here, alive and happy, 16 years later. This feels like an impossible thing. I realise now that, growing older, we can uncover magic as often as we leave it behind.

And there is always the possibility, the sweetest possibility, that we might – just might – enjoy ourselves.

A Boy Called Christmas by Matt Haig (£12.99, Canongate) is out now. To order a copy for £10.39, go to bookshop.theguardian.com or call the Guardian Bookshop on 0330 333 6846.

In the UK, the Samaritans can be contacted on 116 123 or samaritans.org. In the US, the National Suicide Prevention Hotline is 1-800-273-8255. In Australia, the crisis support service Lifeline is on 13 11 14. Hotlines in other countries can be found here.