A recent study has found that having someone within your network who causes you stress – described as a “hassler” – can add roughly nine months of extra biological age and cause cells to age about 1.5 per cent faster per year.

“When we’re regularly exposed to difficult or emotionally draining relationships, the body activates a chronic stress response,” says Dr Nirusha Kumaran, a GP and functional medicine specialist. “Over time, this leads to sustained elevations in stress hormones such as cortisol, which can lead to biological wear and tear, accelerating cellular ageing.”

Ageing cells can increase your biological age and are linked to higher risk of disease, slower recovery, less energy and wrinkles.

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The study was published in the journal Proceedings of the National Academy of Sciences. “Studies like this reinforce something we are increasingly seeing in medicine: that our social environment has a measurable impact on our biology, not just our mood,” adds Kumaran.

So what other everyday experiences or habits could be ageing us?

Your sleep schedule

Ever woken up after a poor night’s sleep and just felt… old? Sleep is one of the best healthy-ageing tools, however. The amount of sleep you get, and the time you go to bed and wake up, can make a difference to ageing.

“Going to bed and waking up at different times each day disrupts your circadian rhythm, your internal 24-hour clock that governs everything from hormone release to cellular repair,” says Kevin Leivers, pharmacist and founder of The Naked Pharmacy.

A Finland-based study, published in the journal BMC Cardiovascular Disorders, found that irregular bedtimes increase the risk of cardiovascular issues such as heart attack and stroke. The risk was even higher in people who also slept less than eight hours.

“During sleep, the human growth hormone is released, cells regenerate, and the brain clears waste products linked to cognitive decline. When sleep timing shifts consistently, these processes are disrupted, so over time, the cumulative effect can accelerate biological ageing,” adds Kevin.

While a single late night is unlikely to have any lasting impact, Kumaran says that repeated inconsistency, known as “social jet lag”, can. Even a 90-minute shift in sleep timing across the week – think 10pm one night and 11.30pm the next – can cause problems.

Poor gut health

Your gut isn’t just a digestive organ, it’s a longevity organ.

“When the balance of gut bacteria in your microbiome – the collection of trillions of different bacteria – is disrupted, this can increase low-grade inflammation in the body. Chronic inflammation is one of the key biological processes linked to accelerated ageing,” says Dr Megha Pancholi, clinical lead GP at Boots Online Doctor.

A study published in the journal Aging suggests that people who live to 90 and beyond actually have more diverse gut bacteria than younger adults, which challenges the accepted idea that the gut microbiome declines with age.

The good news is that you can improve your microbiome: pack in more fibre to feed the good bacteria, and eat vegetables, legumes and wholegrains. Kevin suggests fermented foods such as kefir, live yoghurt and sauerkraut, which all help to introduce different strains of good bacteria into your microbiome.

Doom-scrolling

Short-form videos, which dominate your Instagram and TikTok feeds, could be ageing your brain.

A research review in the International Journal of Adolescence and Youth found that people who overuse short videos tend to have shorter attention spans and even a weaker memory. There’s no official number on how much is too much, but the more often and compulsively you scroll, the greater the impact on your brain.

“These platforms encourage frequent spikes of [the] feel-good hormone dopamine, which can increase restlessness, reduce attention span, and importantly, interfere with sleep quality and mental recovery,” explains Kumaran. “Often, the indirect effects such as poor sleep and higher stress from short-form videos can influence long-term health and ageing.”

Your same-old same-old routine

Doing the same thing every day, morning until night? Give your brain something new to get its teeth into.

“From a longevity perspective, the brain is a demand-driven organ,” says Dr Sophie Shotter, founder of the podcast, Age Well with Dr Sophie Shotter. “It adapts to the level of challenge it is exposed to. When daily life becomes overly routine and cognitively undemanding, the brain receives fewer signals to maintain and strengthen its neural networks. This reduces neuroplasticity, the brain’s ability to form new connections, and causes a decline in factors such as brain-derived neurotrophic factor (BDNF), which helps brain cells grow and stay healthy.”

Over time, your brain becomes less resilient and less able to cope with wear and tear as you age.

“This is a reason why individuals who remain intellectually engaged throughout life tend to have a lower risk of cognitive decline and dementia,” says Shotter.

Support your brain’s longevity by regularly introducing daily tasks that feel slightly effortful or unfamiliar. Even 10 to 20 minutes can help.Try a daily crossword, learning a new language or recipe, joining a debate group, or even volunteering with a group of new people.

Sitting down too much

Many of us spend around nine hours each day sitting down, according to the NHS. But all this sitting does you no favours, especially when it comes to ageing.

Research involving 5,578 women in the journal Aging Clinical and Experimental Research found that after sitting for seven hours, every extra hour of sitting increased ageing risk by around 12 per cent as it may increase inflammation and affect body systems linked to ageing such as kidney function and muscle health.

When you sit for long periods, your body starts to “slow down”.

“When we move, muscles release signalling molecules known as myokines, which have anti-inflammatory and protective effects throughout the body. Sitting for too long reduces this signalling, contributing to chronic low-grade inflammation, often referred to as ‘inflammaging’, linked to aging and disease,” adds Shotter.

“Reduced movement also leads to decreased blood flow and less healthy blood vessels, both associated with cardiovascular ageing, and can lead to an increase in metabolic disease such as type two diabetes.”

A single session of exercise won’t offset a day of sitting. “Break up periods of sitting every 30 to 60 minutes. Stand, walk during a phone call, or stretch for a few minutes,” adds Shotter.

Negative self-talk

When you look in the mirror, are you kind about yourself or constantly picking out flaws in your appearance and personality?

“Persistent negative self-talk can act as a form of ongoing internal stress,” says Pancholi. “This can keep the body’s stress response activated for longer periods and increase stress hormone activity.”

Your thought patterns alone don’t determine biological age, but they can influence sleep, activity levels and diet, as well as the body’s stress and inflammation pathways.

“Shifting this pattern often starts with awareness,” says Pancholi. “Notice negative thoughts, challenge whether they are accurate – hint: they’re probably not – and reframe them in a more balanced way.”

Instead of thinking, “I’m awful at everything”, try, “I didn’t do well at this, but I can improve.”

Or instead of “I look bad today”, try “I’m having an off day and that’s okay”.