She adds: "At home, my husband Gregor was becoming quite shocked by me. I had started to argue about very small things. I would be super angry and very aggressive, even if he moved the milk, for example. I had been an easy-going person; now a degree of gentleness had disappeared out of me. My children noticed and I became burdened by conflict."
Borelius's story is not unusual, says Dr Angelina Nizzardi, a health coach and therapist in Bedfordshire. While rage affects both sexes in mid-life, women can be particularly susceptible to outbursts.
"I see a lot of women in mid-life who suffer with anger and stress or overwhelm issues. Often, they haven't experienced such emotional volatility since puberty." She cites a recent client who came to see her after a rage incident. "She was riding her horse in a field when a person went past her, walking their dog along a public footpath.
"The horse was slightly startled and flicked its head. But that was enough for my client to unleash a tirade of bile, as she put it herself, at this dog-walker. She told me it was like a fire in her belly."
Dr Nizzardi adds: "Her behavior left her with terrible feelings of guilt and shame."
Flipping into an angry state often happens when we feel vulnerable or bad about ourselves, says Dr Elena Touroni of The Chelsea Psychology Clinic. "We can't manage that psychologically," she explains. "Rage is a coping strategy. It doesn't get you where you want to go, but most of us tend to find anger easier than other emotions."
The reasons for our collective tantrums are not hard to find. According to research at Iowa State University, losing just a couple of hours of sleep at night makes you angrier, especially in frustrating situations.
Its research, published in the Journal of Experimental Psychology: General> last year, found that sleep-restricted individuals showed a trend towards increased anger and distress, essentially reversing their ability to adapt to frustrating conditions over time.
For women, says Dr Nizzardi, much of a woman's mood changes are also related to hormonal changes. "Progesterone and estrogen begin fluctuating during mid-life," she says, "and that creates mood swings, anxiety, irritability and angry outbursts.
"In particular, lower levels of progesterone are the issue, as it acts as a natural sedative. The changing levels of your hormones also interrupt the messages passed by neurotransmitters in your brain.
"So your adrenaline can get stimulated by a tense situation but your brain doesn't get the message to produce serotonin, which would help you stay calm."
But our stages of life are also a factor, which affects men and women equally, she says. "I think it's the uncertainties that come at this stage. You may be feeling disappointed, fearful or frustrated at where you are in your career or personal life."
However, she points out, it doesn't always have to be negative. "Self-reflection can be great when it acts as a springboard for change.
"It's important to establish where you are, accept it and then make some changes."
Psychologist Dr Meg Arroll agrees. "Both sexes suffer similar pressures. It's part of being the sandwich generation: you may have children or young adults on one side and you're caring for your elders on the other. There can be financial pressures, too. You get pulled in so many directions at this time of life and start to feel you are never really good enough."
Summer often brings it all to a head, she adds. "Planning a summer holiday means allowing for all the work that needs to be done in advance before you even leave. And if you are at home, and the sun does come out, you may feel too guilty to sit outside for a bit and just enjoy it."
For Maria Borelius, a decision to look at all the aspects of her life that were making her unhappy – not just the loss of temper – was key to resolving her issues.
She says that at the time, her mother, who lives in Sweden, was poorly, her children were beginning to leave home, and middle-aged weight had crept on in the shape of a "muffin top". Worst of all, Borelius was living with chronic backache.
Borelius decided to seek out a trainer who could help with the physical symptoms and was placed on an anti-inflammatory diet combined with exercise, meditation or stillness. She was intrigued to notice that the first thing to improve was her mood – but after two months, all her symptoms were getting better.
"There is a lot of good research which shows the low-level systemic inflammation many of us live with as we get older – thanks to our diets, age and stress – affects our brain chemistry. When you lower your levels of inflammation throughout the body, everything improves. Particularly mood."
The connection between ire and inflammation, which is associated with such chronic illnesses as heart disease, arthritis and cancer, seems like a vicious circle. Recent research published by the American Psychological Association in the journal Psychology and Aging> has found that anger – possibly due to bereavement or a loss of physical mobility – can itself lead to increasing levels of inflammation.
As a result of her own experience, Borelius has written a new book, Health Revolution: Finding Happiness and Health Through an Anti-inflammatory Lifestyle, aiming to share the science behind her transformation.
"I used to say my mood is bad because my children are leaving home and everyone is an idiot. But now I think there is a root cause in systemic inflammation – deal with that and all the symptoms are managed."
Using meditation or stillness as a tool can be really helpful to lowering anger levels, agrees Dr Nizzardi. "It is not always possible to overhaul our lives," she points out, "but we can take these small moments for ourselves."
