Sarah Lazar's voice was calming even over the phone as she demonstrated, for this interview, a typical start to a mindfulness practice. "Notice you are breathing in and breathing out. Can you just be aware and really feel what it feels like as air passes through your nostrils?" she asks, gently.

"It may sound incredibly boring," she says with a chuckle. "But things start to quiet down inside."

According to Lazar, assistant professor of psychology at Harvard University, observing your breath without self judgment actually changes the way your brain is wired.

She ought to know. As the lead researcher of a series of studies on yoga and meditation based at Massachusetts General Hospital, Lazar and her team have found that practicing things like yoga and meditation go far beyond a simple de-stress session and are, in fact, surprisingly long lasting.

Thanks to what we know about the science of neuroplasticity - the brain's way of reshaping itself to adapt and grow - Lazar and her team have shown that the practice of meditating  - or quieting the mind - is not a passive act, even if it does involve sitting silently with eyes closed. On the contrary, it's an extremely active endeavor. Meditation significantly alters the regions of the brain associated with stress, overall well-being and fluid intelligence.

After suffering from a running injury, Lazar was told that she would need to stretch regularly; as a result, she decided to try yoga. Despite being a self-described "total skeptic" about there being additional benefits of yoga beyond the physical ones, Lazar soon begin to notice a profound shift in her mindset.

"It really changed how I thought about things, how I saw and interacted with the world. It made me much calmer," Lazar reflects. "I knew beyond a shadow of a doubt that my brain had changed. I was just thinking about things differently than I had before." She has been pursuing a Ph.D. in molecular biology at the time but shortly thereafter switched her research to focus on yoga and meditation.

In her initial study, Lazar and the team attempted to determine if differences existed in the brains of long-time, regular meditators - as compared with those of non-meditators. By scanning their brains using Magnetic Resonance Imagining (MRI), researchers were able to see that the brains belonging to regular practitioners were thicker in parts of the cerebral cortex. Moreover, these thickened areas were linked to brain functioning related to decision-making, memory and attention, as previous research has revealed. But even while these particular images seemed to suggest that the cerebral cortex growth might have been a result of the meditation practice, it was not possible to say for sure.

To gain more clarity about meditation's precise effects on the brain, the team delved deeper, attempting to determine whether meditation could alter the brains of subjects who had never meditated. In doing so, they chose to employ Mindfulness Based Stress Reduction (MBSR), an eight-week meditation program, and use it with first-time meditators. Participants, age 25-50, who indicated feeling "stressed" and were in relatively good health, were invited to join the study. Study subjects also had to be free from anxiety and depression and not on any kind of medication, which Lazar explained could skew the study since drugs of all kinds have the potential to affect the brain. As the study got underway, subjects were tasked with completing a questionnaire designed to gather self-reporting on stress levels and general well-being. Next, the subjects were given MRIs that were used for baselining. After half the group completed the eight-week meditation course, those individuals were tasked with completing the same questionnaire and then scanned a second time.

By comparing the subjects' reports with their brain scans, the team observed that participants were feeling less stressed while also expressing feelings of a greater sense of well-being - all that in just eight weeks.

More important for the study, their brain scans reflected the emotional shift. Reports of lower stress levels correlated with reduction in the amygdala, the brain's center of fear and anxiety. (At the time of Lazar's study it was already well known that the amygdala fluctuates in size, growing larger when exposed to stress hormones). Lazar's team also showed that a greater sense of well-being correlated with growth in the brain stem, which is where the so-called "mood molecules," dopamine and serotonin, are produced.

Although the research team can't say for certain what exactly goes on in the brain stem after practicing meditation, the eight-week study was enough to back the hypothesis that it played a key role in the observed changes.

The team's latest study has revealed that meditation also helps preserve overall brain function.

Examining the brains of older meditators and yoga practitioners, age 40-70, compared with non-practitioners, the team found that meditators and yoga practitioners showed less deterioration in "fluid intelligence" than those in the non-meditating group. Lazar defines "fluid intelligence" as the neuron-based process that allows different regions of the brain to communicate with one another, providing us the ability to problem solve.

Fluid intelligence tends to decline as we age, which means no one in the either test group was completely immune to the effects of age-related brain deterioration, but the results of this cross-sectional study showed that yoga and meditation began to chip away at the aging process by slowing the predictable decrease in communication between neurons. 

So far, Lazar's studies have mainly focused on subtle, gentle yoga and meditation that encourage the practice of "listening" to your body and actively "tuning in" to its breathing - in other words, practices that focus on honoring your limitations rather than getting into "pretzel poses," as Lazar puts it. On the whole, she believes these studies represent the first steps in understanding how meditation and yoga work on us.

Her team is currently expanding its focus to examine the effects that similar meditative practices like Tai Chi and more advanced forms of yoga have on our brains. Lazar also sees these studies as an opportunity to learn which meditative practices work best as directed therapies, so it's not a "one-size- fits-all" outcome. Still, Lazar emphasizes that even the most basic of meditative practices are worth the effort.

"It really can benefit everyone," Lazar answers, perhaps in answer to the skeptics she once counted herself among.