Breakups are not much fun.

Whether it’s your first time through it or an unfortunate familiarity, there are few more agonising gut punches.

Doubts and insecurities aplenty; wondering where, how and why things changed; and like an agonising Lionesses World Cup run, an overwhelming sense of “what if”.

Being a “science and tech journalist” has given me a fresh perspective on how it can impact us physically.

Where’s that headache come from? What about a sudden lack of energy? And why does eating anything, even a normal favourite, feel like an I’m A Celebrity challenge?

For when pictures of wistful poetry on Instagram just don’t cut it, it turns out science has some answers.

The holy trinity

As neuroscientist Dr Lucy Brown puts it, “we’re all miserable when we’ve been dumped” – and there’s a potent chemical cocktail that helps explain why.

Serotonin is the brain chemical associated with happiness, oxytocin with bonding, and dopamine gets pumped out whenever your mind’s reward system kicks in.

No surprise then that you feel good when that holy trinity is high and rough when it’s low.

The key chemical is dopamine: the ultimate natural drug.

‘It’s like we’re addicted’

Brown was one of a team of researchers who conducted a study into the impact of heartbreak, scanning the brain activity of 15 young adults who were going through unwanted breakups.

They were shown photos of their ex-partners, and the scans showed parts of the brain that power our sense of motivation and reward – where our dopaminergic neurons live – went into overdrive.

It’s an “overactivity” Brown compares to what you’d see in a cocaine addict trying to wean themselves off.

“It’s like we’re addicted to each other,” she says.

“When we lose someone, we’ve lost a very rewarding part of our lives and sense of self. They’ve provided novelty in your life that now isn’t there, so we need some other rewards.”

And like rewatching goals we may have thought had put the Lionesses’ name on the title, looking back at texts and holiday photos won’t do the trick.

A body under threat

Florence Williams had found herself intrigued by the pain her heartbreak caused.

Having seen her 25-year marriage suddenly fall apart, trauma was expected. But feeling physically sick and totally overwhelmed took her by surprise.

“I was of course stunned by the event itself, but then I was really confused and surprised by how different I felt physically going through it,” she says.

“That feeling of being plugged into a faulty electrical socket; this buzzing sense of background anxiety and hypervigilance and an inability to sleep well; the weight loss and general confusion.

“My body felt under threat.”

Williams’s experience and sense of confusion sent her on a global quest for answers documented in her book, Heartbreak: A Personal And Scientific Journey.

She found while everyone’s personal heartbreak is different, the bodily response is much the same: it’s time for that holy trinity of hormones to take a battering.

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‘Very real’ physical symptoms

And it’s not just emotional pain you may struggle with. In Brown’s study, brain areas associated with physical pain were also activated.

She explains rejection triggers a part of the brain called the insular cortex – the same part that responds to distress around pain, like when panic sets in after an already painful bee sting.

When emotional stress causes physical symptoms, like headaches and nausea, its medical term is somatisation.

“If you’ve ever had butterflies when you’ve been nervous, you’ve experienced this,” explains Dr Abishek Rolands.

“The most important thing to remember is even though there is no physical cause, the symptoms are very real – they are not made up or ‘all in the head’.”

During her research, Williams, who has two adult children with her ex-husband, was particularly fascinated by the impact loss can have on our immune system.

“It’s important for our nervous systems that we feel safe,” she says.

“If we have people in our lives triggering cascades of healthy hormones, it’s really protective against illness. Our cells actually listen to our mental state.”

Indeed, previous studies have stressed the importance of meaningful social relationships to stay healthy.

And in 2021, US researchers suggested our immune system takes cues from our nervous system if it’s struggling – effectively making decisions that could make us sick.

Broken heart syndrome

In rare cases, this kind of emotional distress – especially when delivered suddenly – can even lead to the fittingly nicknamed “broken heart syndrome” – or takotsubo cardiomyopathy.

Sindy Jodar, a senior cardiac nurse at the British Heart Foundation, says the symptoms – chiefly shortness of breath and chest pain – are consistent with a heart attack.

“Most people have either been under a lot of physical or emotional stress, like losing a loved one,” she says.

“The only explanation we have at the moment is when the body is stressed, it releases a lot of catecholamines (adrenaline), and when lots of that is around in the body it can impact the heart.”

Unlike a heart attack, the condition does not cause blockages in the coronary arteries – but does totally change the shape of the heart’s left ventricle, which pumps oxygenated blood through the body.

It’s this which gives the condition its actual Japanese name, as the shape of the ventricle becomes reminiscent of a trap fishermen use to catch octopus: narrow at the top, larger at the bottom.

The condition only impacts around 5,000 people a year in the UK, and is more common in menopausal women, with most recovering after a few weeks.

Giving up the addiction

Just as science can explain why heartbreak, rejection, and loss makes us feel the way we do, it also offers solutions.

Brown says heartbreak should be treated like “having to give up an addiction”, though she admits the “craving is stronger when we’ve lost someone”.

But there are plenty of roads to go down without gorging ice cream while watching La La Land.

Williams stresses the importance of working to activate the parasympathetic part of your nervous system by doing things that make you feel calm. The other part of our autonomic nervous system, sympathetic, is what causes anxiety and hypervigilance.

“Connection to nature is really calming,” she says, likewise to friends and family. “And there’s lots of data showing the more meaning you derive from work, the more purpose you feel, the happier you’ll be.”

Williams says such lessons apply to anyone “going through an emotional life quake”.

“People who end a relationship also face big emotions – guilt, sadness, loneliness,” she adds.

And as Brown says, there’s novelty – that sense of excitement that needs refreshing in a healthy, sustainable way.

Ice cream makes a compelling dinner once, but you’d probably best hope it wears off.

“A good strategy is beginning things you didn’t do during a relationship, like running or travelling,” says Brown.

“People always remember a heartbreak – it’s very painful. But you do change, and can for the better.”