Iwas in the truck with my brother Ian. He was driving, so based on the universally accepted custom, he got to DJ. His chosen music was … loud. Really, really loud. Was it AD/DC? Metallica? The vocalist was screaming in … what? Anger? Sadness? Just to scream? I couldn’t quite tell, for my ears had filled with blood, rendering coherent thought impossible.

Ayurveda, yoga’s sister science, is a system of holistic wellness thousands of years old. Ayurveda holds there is a crucial difference between noise and sound. A sound is something pleasing to the ear. Illustrated visually, the wave for a sound appears smooth and at more regular intervals. A noise is any unwanted sound. Sound waves from noises appear more jagged and sporadic.

Most people consider natural sounds, things like birdsong or a babbling brook, as pleasing. Noise often arises from man-made things; think traffic, lawnmowers, or the incessant beep of incoming phone notifications.

Of course what one person considers a beautiful sound, the next interprets as horrible noise. Ian was radiating happiness listening to heavy metal, where it was setting my teeth on edge and making me a little sick to my stomach.

This isn’t an accident. The word noise is actually derived from the Latin word nausea, meaning seasickness or, well, nausea. And regardless of what you personally consider pleasing to the ear, each of us is besieged by far too much noise and not enough silence.

Loud noises (those over 30 decibels) activate the brain’s amygdala, resulting in a release of the stress hormone cortisol in the blood. Over time, these elevated cortisol levels can damage our hearing, interfere with restful sleep, raise our blood pressure, cause weight gain, negatively affect stress levels and trigger migraines.

A 2001 study published in the Journal of the Acoustical Society of America found that Austrian children who live in neighborhoods with constant low-level noise (those living near intersections, airports, and train crossings) had far higher levels of cortisol than kids who lived in quieter neighborhoods.

Florence Nightingale, the 19th century British nurse and social activist, certainly believed this. She argued that, “Unnecessary noise is the most cruel absence of care that can be inflicted on sick or well.”

The reverse is true as well. Silence can help heal our bodies, minds and souls. Before any of us existed, the universe was a vast vacuum of sound. It is our natural state.

By bombarding our bodies with more and more noise, we set the groundwork for physical illness and mood disorders. But in silence, we lower the cognitive load on the brain so that it may reset itself (science calls this “attention restoration theory”). When you actively choose to be silent for part of the day, the brain can literally let down its sensory guard to focus on growing stronger. Yes, that’s right. Silence actually grows brain cells!

A 2013 study, published in the journal Brain, Structure, and Function, involved comparing the effects of ambient noise and silence on the brains of mice. They found that two hours of silence daily led to an increase of new cells in the hippocampus, a key brain region associated with learning, memory and emotion. Further, sitting in silence for only two minutes improves your blood circulation and lowers blood pressure. If we make it a daily habit, we can, over time, lower our risk of heart disease and improve our stress levels.

I think of silence as preventive medicine for my mind and body. I consciously spend a few minutes each morning and each afternoon in total silence. Remember how I said there is a difference between sound and noise? Silence is absent of man-made noise, but it isn’t completely devoid of sound. The more you choose silence, the more you notice the subtle sounds around you. As I write this, I can hear rain on our roof, birds singing in the distance and the rise and fall of my breath. This silence boosts my immune system, mood and energy level.

Try it for yourself. Set down the paper and get comfortable, either sitting with good posture or lying down. Close your eyes. For a few minutes, just listen to the sound of your breath entering and exiting the nose. If a noise interrupts you (the cell phone rings or you become conscious of the neighbor’s lawn mower), simply notice the noise and then draw the attention back to your breath. For two full minutes, just be quiet. Doesn’t that sound great?

Erin Smith is the owner of the OM place in Winchester, the author of “Sensible Wellness for Women” and the online host of a yoga and mindfulness channel for Eppic Films. Send her a shout out at erin@theOMplace.net or play along at www.theOMplaceChannel.com.