Sleep Rhythms: And the Beat Goes On

Sound Brain Fitness Series

Your brain is a grey, wet, squishy pattern seeking machine.  From daily changes in light to microsecond scale responses to music and voices, your brain runs on and generates the rhythms of your life.  And because we are so rhythmocentric at such a basic level, events that violate your normal rhythms often have serious impacts on us.  The field of chronobiology examines how the timing of environmental and internal events affects our cognition, our health and our daily life, whether it’s transient like focusing on a task or longer term like getting enough sleep.

Next week is National Sleep Awareness Week 2013. To kick it off I’ve invited neuroscientist and author Dr. Seth Horowitz back as my guest for another episode of the Sound Brain Fitness teleseminar series. Please join us for this free teleseminar on Monday evening, March 4th at 8 pm eastern for what is sure to be an engaging hour as we explore:

  • Rhythms of the environment and how they affect the rhythms of the brain
  • Rhythms and patterns of sleep – where they come from and what they do.
  • Interrupted sleep patterns – the consequences of insomnia, disruption, and EDS
  • Weapons of choice – tools for resetting the sleep clock and their side effects
  • Why an auditory sleep aid may be right for you

I hope you’ll listen. You can register here.

Rock-a-bye Brain

A Good Laugh and a Long Sleep

Guest Post By: Seth Horowitz, Ph.D., Neuroscientist and author The Universal Sense

Sometimes the best science is done by looking at the obvious — the daily behaviors that we do — to solve a mystery.  And watching almost any sleep-deprived parent and his or her young child will give you an instant insight into two powerful mechanisms that underlie human sleep, one of neuroscience’s greatest mysteries, as the parent rocks his or her infant back and forth, crooning a lullaby.  These are two behaviors that have probably been used by humans seeking sleep for their children (and themselves) since humans first appeared, and both are driven by our ears.

It may seem odd to think that rocking someone to sleep has anything to do with your ears, but your ears contain two sensory systems — the auditory system for hearing sounds, and the vestibular system, which normally underlies balance.  Both are driven by similar types of sensors, called hair cells. These are tiny, tufted cylinders with tips that wave back and forth in fluid -filled chambers, each responding to different types of motion: oscillations of pressure waves that are translated into sound, and slower, linear or angular motions based on how the head moves (which drives balance).

Normally, the two systems are separate, projecting to different areas of the brain and helping define different ways in which we sense our environment.  But both systems can overlap under certain circumstances. Managing sleep is one of the most profound ways in which they interact.

Balance and the Vestibular System: your brain’s way of processing movement

One of the things that the balance system does is let us know when things are wrong with the way we are moving.  Standing on a boat in high seas, your vestibular system will tell you that the world is moving up and down at one rhythm, while your stomach and eyes are experiencing movement in different directions.  Radical motions that separate what your inner ears and your eyes tell you are happening trigger nauseogenic motion sickness.  But slow down the motion, make it almost regular, slower, and gentler, and your inner ears do something odd.  They put you to sleep.  Whether it’s a baby rocking gently or a passenger in a car, bus, or train, gentle vibrations transmitted through your body to your inner ears trigger another form of motion sickness. It’s called Sopite syndrome, and, rather than making you want to lose your lunch or die, it activates your global sleep network.  But it’s not always convenient to drive your child around on bumpy roads to get her to drift off, or possible to rock your baby in a quiet environment.

Low frequency sounds: feel the beat

This is where the other part of your ears can help.  While normally there is no cross talk between your hearing and balance system, high pressure/low frequency sounds can trigger responses in the balance-sensitive hair cells in your ears.  This is why most effective dance music pumps up the bass, hijacking your sense of hearing to trigger motor responses. In other words, rhythmic deep bass sounds make you feel the beat and want to match it with body motion.

But the truth is, we don’t hear very low frequency sounds very well, and even sound pressure levels of 70 dB — what would seem like a moderately noisy street or bar scene at higher frequencies — are perceived as relatively quiet at lower frequency.  And here lies the opportunity.  By providing semi-regular, low frequency sounds that are audible, but not loud enough to make you want to dance or run away, you can trigger Sopite syndrome and provide a gateway to sleep.  And by providing soft, regular sounds in a familiar register (like the universal aspects of lullabies, which stretch back more than a thousand years), you block out the distracting environmental sounds that can interrupt falling asleep.

The Listening Program® SLEEP uses those combinations of sounds so that your ears tell your brain it’s time to sleep. You may not feel like you’re being rocked like a baby, but your brain will get that impression. And it’s all due to the two functions of your ears.

So the next time you do bundle your cranky child into the back seat of your car and finally get her to fall asleep, remember to thank her ears.  Just make sure you don’t let yourself get lulled by those very same inputs to your own brain.

Follow @SethSHorowitz

Sound’s Dual Personality

Sound's Dual Personality

Dual personalities, when it comes to people, we understand the connotation. But did you know that sound also has a dual personality? One harming, and the other healing…

This is the premise of the feature article in the Winter 2013 issue of Hearing Health Magazine from the Hearing Health Foundation. Journalist Elizabeth Stump interviewed me, and my friend, neuroscientist and author of The Universal Sense, Seth Horowitz, for an exploration into the fascinating world of sound. You can read it starting on page 26 of the online edition here. You can also find my interview on the importance of respecting sound on pages 30-31.

Please share your comments here, or on Facebook.

The Universal Sense: How Hearing Shapes the Mind

Two days ago a fascinating book came out by my friend Seth Horowitz. The book is The Universal Sense: How Hearing Shapes the Mind.  Seth is a musician with a day job as a neuroscientist at an Ivy League University. He has a seemingly endless imagination and childlike curiosity for all things vibrational.   These attributes coupled with an uncanny ability to explain complex information with ease, and a wicked sense of humor, equip him a skilled writer who crafts an entertaining read!

About the book— Every day, we are surrounded by millions of sounds – ambient ones like the rumble of the train and the hum of air conditioner, as well as more attention-grabbing sounds, such as human speech, music, and sirens. But how do we process what we hear every day? And how does it affect our brains and our minds?  This book answers such revealing questions as:

  • How do bats see in 3D with their ears and how did that lead to the development of medical ultrasound?
  • What is it about the sound of fingernails on a chalkboard that makes us cringe?
  • Why do city folks have trouble sleeping in the country, and vice versa?
  • Why can’t you get that song out of your head?

Starting with the basics of auditory biology, neuroscientist and musician Seth Horowitz explains how sound affects us, and in turn, how we’ve learned to manipulate sound: into music, commercial jingles, car horns, and modern inventions like cochlear implants, ultrasound scans, and the mosquito ringtone. Whether you’re standing in a crowded subway or a quiet meadow, you’ll never hear the same way after reading this book. The Universal Sense gives new insight into what the sounds of our world have to do with the way we think, feel, and interact.

I cannot recommend this book highly enough, but so do others including Publishers Weekly. Here’s what they have to say…

Brown University neuroscientist Horowitz has pulled off an unusual feat. His science book, about the way hearing shapes the “evolution, development, and day-to-day function of the mind,” can be genuinely poetic. It is also laced with humor. Horowitz says he attempted less a text than a venue for imparting “wonder.” He succeeds, unearthing one little-known gem after another.

I should mention that Seth serves on the Scientific Advisory Board at Advanced Brain Technologies. He is working with us on a number of interesting projects with his partner at Neuropop, musician, composer, and technologist Lance Massey. Exciting things ahead!

Connect with Seth— Twitter, Facebook. Listen to a recording of a recent teleseminar he did with me for my monthly Sound Brain Fitness Series The Auditory Brain.

Watch for upcoming guest posts from Seth here at The Brain Understanding Itself.   Read  The Universal Sense.