Have you ever noticed that after a few hours of real silence — no music in your headphones, no notifications, no TV murmuring in the background — your mind feels like it’s been rebooted? Thoughts become clearer, old ideas resurface, emotions calm down a bit. Most people chalk it up to simple rest. But something deeper might be happening: silence may literally trigger the brain to grow new neurons.

In 2015, an unusual study appeared that still sparks debate today. Researchers (a team led by Imke Kirste and Daniel Ziegler) at Duke University decided to test how different sound environments affect the hippocampus in mice — the same brain area in humans that turns short-term memories into long-term ones, helps us navigate space, and regulates anxiety.

They divided the animals into four groups:

• The first lived in normal lab noise (about 50–60 dB — like a quiet conversation).
• The second heard white noise.
• The third listened to Mozart (yes, they tested the famous “Mozart effect” again).
• The fourth spent two hours a day in near-total silence (below 20 dB — almost complete sound isolation).

After several weeks, the mice from the “silent” group had significantly more new neurons in the hippocampus than any other group. White noise and Mozart? Zero effect. Regular lab noise? Almost nothing. Only silence triggered neurogenesis.

The original study really exists (though the viral version floating around social media is heavily simplified). The actual paper is titled “Is silence golden? Effects of auditory stimuli and their absence on adult hippocampal neurogenesis” (Imke Kirste et al., Brain Structure and Function, 2015). Full silence was just one variable in an “impoverished vs. enriched environment” experiment, and the results were more nuanced than “silence = brain superfood.” Still, that mouse study became the foundation for thousands of popular posts claiming “silence heals the brain.”

Here’s the fascinating part: later human studies (though less extreme) point in the same direction.

For example, a 2006 study published in the journal Heart by Luciano Bernardi and Bernardo Dubey found that even brief, two-minute pauses of silence between music tracks were more relaxing to the brain than the "relaxing" music itself. During these silent pauses, researchers recorded a significant drop in heart rate and blood pressure, indicating a surge in parasympathetic nervous system activity (our “rest and digest” state). This suggests that the brain and body are actively responding to silence as a profound signal to recover. Other research suggests that this state of quiet internal focus is linked to elevated levels of BDNF (brain-derived neurotrophic factor), a protein often called “fertilizer for neurons.” BDNF helps newborn cells survive and integrate into existing networks.

So even if mice aren’t humans, the mechanism looks similar: when external stimulation drops to almost zero, the brain stops spending energy processing noise and redirects it toward internal “repair work.”

What does this actually mean for you and me?

The hippocampus is one of the few areas of the adult human brain that can still produce new neurons throughout life. Yet the average person today is exposed to 8–11 hours of sound stimulation every day (work, traffic, podcasts, background Netflix). We’re voluntarily creating conditions in which the hippocampus never gets a chance to take care of itself.

A few numbers to grasp the scale:

• Open-plan office noise often exceeds 65–70 dB — enough to raise cortisol (the stress hormone) 20–30% within hours.
• Listening to podcasts or music at 60–70% volume blocks the default mode network — the brain’s “daydreaming” system that activates only in quiet and is responsible for creativity and self-reflection.
• People who meditate regularly (and meditation is essentially controlled inner silence) have greater hippocampal volume than non-meditators, according to long-term research from Harvard (led by Sara Lazar, 2005–2021).

How to add silence when you’re not a monk living in a cave

You don’t need to disappear into a monastery. A few simple habits actually work:

• Two hours a day without headphones or background sound. Just walk, wash dishes, sit — no podcast. Most people say the first 15 minutes feel like panic (“what am I missing?”), then a strange, calm happiness sets in.
• A full “quiet hour” before bed — not 10 minutes, a whole hour without screens or sound. This practice is one of the most powerful ways to improve sleep quality by allowing the brain to power down naturally.
• Walks in a park or forest without earbuds. In Japan it’s called shinrin-yoku — forest bathing. Measurements show 40 minutes of natural silence (or the gentle sounds of nature) lowers amygdala (anxiety center) activity by 20–30%.
• One day a week without voice messages or calls. Text only. Sounds scary, but try it — it’s like a fasting day for your brain.

A conclusion that doesn’t sound like a lecture

Silence isn’t emptiness. It’s the space where the brain finally gets to rebuild itself. We’re used to thinking growth demands effort — books, courses, biohacks. Turns out one of the most powerful things we can do for our mind is simply shut our ears and let it be alone with itself for a while.

Try turning everything off for just half an hour today. Not to “meditate correctly,” just to listen to what your own silence sounds like.

It might tell you something important.

Sources:

• Imke Kirste et al. “Is silence golden? Effects of auditory stimuli and their absence on adult hippocampal neurogenesis” (Brain Structure and Function, 2015) — the original mouse study.
• Luciano Bernardi et al. “Cardiovascular, respiratory, and autonomic effects of music and silence” (Heart, 2006) — the human study on silence and relaxation.
• Sara Lazar et al. “Meditation experience is associated with increased cortical thickness” (NeuroReport, 2005) and follow-up work 2011–2021.

Silence doesn’t shout about itself.

But it works.