The number of people reporting high levels of anxiety have seen a spike during the pandemic. So what is it doing to our physical health? Along with prompting us to eat badly, exercise less, stress can have a profound effect on the immune system.

Cumulative stress, if we don’t manage it, affects us very differently to a brief stress – which can actually have a positive effect. "Acute stress isn’t so bad for your immune system," says Sheena Cruickshank, immunologist and professor in biomedical sciences and public engagement at the University of Manchester. In a short burst of stress – prompted by, say, wanting to win a race or impress in an interview – your immune cells mobilise, explains Cruickshank. "You see increases in some immune cells such as the types involved in killing viruses and recognising cancer cells, and the cells we’re trying to target with vaccines, the lymphocytes – they might transiently increase."

But sustained or chronic stress – as well as being emotionally draining – can suppress our immune system, making us more susceptible to bugs. "If it’s persistently high, the stress hormone cortisol can impact the way your lymphocytes function, which can make them less able to deal with infection," adds Cruickshank.

It’s the reason a stressful event can leave us feeling run down, or trigger a recurrence of cold sores, for instance. "A cold sore is a virus. It’s latent in your body and your immune system is keeping it in check, but when your immune system isn’t working so well, the virus can spring back into life," says Cruickshank.

Indeed, during this period of unprecedented stress, it’s all the more important to ensure you’re doing what you can to support your immune system.

Eat right

Diet is vital – what we eat has a profound impact on the gut microbiome which Dr Jenna Macciochi, immunologist and author of Immunity: The Science of Staying Well, describes as "the instruction manual for your immune system". Essentially, our gut bugs digest the fibre in plant foods we eat, creating byproducts extremely important to health, says Macciochi.

"They’re like our own personalised pharmacy. They enter our bloodstream, shaping and educating our immune cells all over our body, telling them what to do, helping remove any baseline inflammation in our system, calibrating our immune system so it can function well."

Dr Macciochi says it is known that with colds and flu, "alterations to the gut microbiome can affect how severely you suffer, and even how frequently you pick up those infections".

Rather than obsess about having this or that species of gut bacteria, she advises eating to ‘fertilise’ and nourish your microbiome ecosystem, by getting all six plant-based food groups into your diet – fruit, vegetables, wholegrains, legumes, nuts, and seeds (and herbs and spices too.) "Forget about Five a Day. Aim for 30 types per week. You might choose different vegetables, or add lentils to a bolognese. Start slowly and build up gently. This will allow the bugs in your digestive system to adapt."

Mostly, we’re nurturing what’s there – though eating fermented foods like unpasteurised yogurts, kefir, sauerkraut, and probiotics containing lactobacillus and bifidobacteria can introduce bacteria beneficial to the immune system into your gut – and some fresh fruit carries its own microbiome, even if you wash it. And here’s another reason to spend time in nature. "Getting out in green space, breathing and swallowing the microbiome in the air is also seeding our gut," says Macciochi. "Urban areas generally have a less diverse, less favourable microbiome."

Let’s get physical

We know that exercise is mentally and physically destressing, but Cruickshank also notes that "regular moderate exercise gets your immune cells working better".

Subjecting yourself to a little bit of controlled, safe stress helps improve your body’s stress response, says Macciochi. That might be cold water swimming, a cold shower, or an exercise that pushes you a little further such as strength training, high intensity interval training, climbing or running.

There are gentler ways, too, of managing stress, such as meditation and mindfulness. That said, attempting to meditate in stressful moments might tip us into meltdown. "The most immediate tool is just breathing," says Macciochi, who recommends simply slowing down your exhale.

A grim narrow focus – such as a screen – isn’t conducive to relaxation, so it’s also soothing to widen our gaze to a "panoramic vision", she adds. "Go for a walk, go to a window, look far away – again, it sends a signal to the brain that you’re relaxed."

Sleep – which has been hugely disrupted by the pandemic – is "the foundation of the immune system", adds Macciochi, and worrying about insomnia only exacerbates it. Avoid caffeine in the afternoon and have a wind-down period in the evening – with no devices, laptops or screens close to your face for an hour before bedtime as "the light from these devices gives your brain the signal that it’s daylight".

Stretch or do yoga if it relaxes you. Or, weather permitting, watch the sun go down. "There’s new evidence that the type of light that we see during a sunset is really important for setting that biological clock within us," says Macciochi.

A reasonably hot bath or shower about an hour before bed will also prime you to sleep.

The final essential ingredient? Don’t be mean to yourself. "Practising self-compassion has been scientifically shown to help us be more successful in engaging in any changes we want to make," says Macciochi. Self-compassion means taking mindful moments in the day, being forgiving of yourself, letting go of perfectionism: "Sometimes half-right is good enough. It’s so important right now to be kind to ourselves - and it’s also associated with improvements to the immune system." There really is no excuse.

Read more