Meditating can help you relax in the short term, but if you stick with it, it might also steel you against the effects of chronic stress and ageing, a new study finds.

Researchers examined gene expression, cognitive function, and hair cortisol levels in people who have been practicing Transcendental Meditation (TM) for either 12 or 40 years.

Compared to control groups of similarly aged people who don't meditate, those with four decades of experience practicing TM showed reduced biomarkers for chronic stress and biological ageing.

"The lower expression of age-related genes and lower hair cortisol in the TM groups extend the findings of short-term studies indicating these practices lead to healthy ageing and more resilient adaptation to stress," says physiologist Kenneth Walton from Maharishi International University in the US.

TM has ancient origins in the Vedic religious tradition of India, but the modern incarnation was developed and popularised in the 20th century by spiritual leader Maharishi Mahesh Yogi, commonly known as the Maharishi.

The method involves the silent repetition of a personal mantra during two daily 20-minute sessions. Certified instructors follow a standardised system created by the Maharishi to teach TM techniques, sometimes called technologies of consciousness.

"This study provides evidence that long-term practice of TM technologies has a broad range of health benefits at the molecular level," says molecular physiologist Supaya Wenuganen from Maharishi International University (MIU), which was founded by the Maharishi in 1971.

In previous research, Wenuganen and colleagues found 200 differentially expressed genes between TM practitioners and non-meditators. Suspecting potential health benefits from those discrepancies, they sought to learn more with their new investigation.

The expression of genes linked with inflammation and ageing was lower in TM practitioners, the new study found. That includes the SOCS3 gene, which is associated with chronic stress as well as energy metabolism.

The reduced expression of these genes suggests that people who meditate may carry a lighter allostatic load or the cumulative effects caused by chronic stress.

The results also fit with previous findings suggesting TM can improve energy metabolism efficiency.

However, it's important to note these findings don't show direct cause and effect. Those who practice TM may also be more likely to possess another unknown trait that's responsible for the associated benefits, or to be generally more health-conscious, than those who don't practice.

The researchers used electroencephalogram (EEG) recordings to look at cognitive function, another variable known to decline with age. The findings revealed that older TM practitioners had cognitive processing speeds similar to those of younger subjects.

Long-term practitioners of TM also scored higher on the "Brain Integration Scale" (BIS), a metric designed to encompass various cognitive abilities such as attention and reaction time.

"The findings around cognitive function are particularly exciting," says biopsychologist Frederick Travis of MIU. "Both younger and older TM practitioners showed higher scores on the BIS compared to non-meditators. The older meditators performed on par with young controls."

"This reinforces the findings on evoked potential responses," he adds, "further suggesting a protective effect against cognitive decline with age."

The researchers measured hair concentrations of the steroid hormone cortisol along with its inactive precursor, cortisone, finding the ratio of active to inactive forms was lower among TM practitioners than non-meditators.

This, too, hints at lower stress levels and supports other findings that link regular TM practice with reduced stress.

"Cortisol plays a critical role in the body's response to stress, and chronically high cortisol levels are associated with a host of age-related health issues in addition to cognitive decline," Walton says.

"The reduced cortisol-to-cortisone ratio in meditators suggests they have more adaptive reserve, more resilience, contributing to overall health and longevity"