A study of over 160,000 individuals in the US and UK, published in Nature Medicine, has found that people born in the 1990s are ageing biologically faster than those born in the 1960s. Using blood biomarkers to calculate biological age, researchers at the University of Washington determined that each unit increase in ageing markers was associated with an 8% higher risk of developing early-onset cancers, particularly of the lung, gastrointestinal tract and uterus. The trend was most pronounced in the US cohort.

The precise drivers remain unclear, but investigators point to a combination of chronic stress, poor diet and sedentary behaviour. Separate research now shows that midlife habits can directly alter biological age. In a year-long randomised trial of 130 inactive adults, mostly in their 40s, those who began regular aerobic exercise saw their brains appear functionally younger on MRI scans, while the brains of non-exercisers aged slightly. “The brain is modifiable, and exercise is a great way to modify it,” said Kirk Erickson, the study’s senior author at the AdventHealth Research Institute in Orlando, suggesting midlife may be a critical inflection point for brain health.

Sleep quality is equally pivotal. After age 45, the circadian clock shifts earlier, causing earlier melatonin release and spontaneous early waking, which can shorten total sleep and impair the body’s nightly cellular repair. Studies also indicate that sleep regularity—maintaining consistent bed and wake times—matters as much as duration, with irregular schedules linked to higher risks of hypertension and diabetes regardless of total hours slept.

Exercise timing and type further modulate outcomes. Data from the US National Institutes of Health suggest morning aerobic exercise may aid weight loss, while evening resistance training can boost muscle strength and improve sleep quality. Activities such as yoga, nature walks and dancing have been shown to lower cortisol, potentially countering stress-driven ageing. However, static stretching immediately before exercise can temporarily reduce muscle power, so dynamic warm-ups are recommended.

The accumulating evidence is prompting clinicians to view biological age as a modifiable risk factor. Researchers are now planning larger, longer-term trials to test whether structured lifestyle interventions in midlife can delay the onset of age-related disease. The next milestone will be the integration of biological age assessments into routine screening to guide personalised prevention strategies.