What’s The Deal With Motion Sickness?
My favourite quote around motion sickness comes from the book Balance, In Search of the Lost Sense by Scott Mcreadie. In the first chapter, introducing us to the idea of the vestibular system, he writes:
“It’s a common adage among experienced sailors that when you’re sick from the sea, first you’re afraid you’re going to die, and later on you’re afraid that you won’t.”
Despite being the most common form of balance issue, motion sickness is no joke. Many people across the world actively avoid certain types of transport in order to avoid the experience of extreme nausea that awaits them. A big part of the dread comes from the nonsensical nature of the experience. We can logically understand why eating something that our stomach didn’t agree with should give us nausea, but not motion. Moving is one of the most natural things that we do, and it feels really strange that it should cause us to suffer in such an unusual way.
Understanding is one of the best things we can do when it comes to improving our relationships with our brain, so today I would like to try to explain the reality behind motion sickness and how we can work against it.
What Causes Motion Sickness?
You may have found it a little strange that I defined motion as a balance disorder, when most of the time we experience it while sitting down on moving transport. It turns out that balance is a lot more complicated than you may have thought. While we might consider balance to be standing on one leg, balance to the brain is simply defined as the art of staying upright, or not falling over. This applies equally whether we are running on a tightwire or sitting on a chair.
In order to balance we must have 3 pieces of information:
What is the current position of all of the joints in my body?
What does the world around me look like?
Which parts of me are currently moving?
This information is delivered to us via our sense, primarily vision, proprioception and vestibular (balance). Usually when we move around, these senses tend to agree with each other. If my vestibular system detects motion, and my muscles confirm that our legs are moving, and our eyes see the world moving around us, we get a pretty strong vote of confidence that we are indeed moving.
But something weird happens when we add transport into the picture. When we sit in a passenger seat of a moving vehicle, our vestibular system will still detect motion, but the other systems will disagree. As far as the body is concerned we are sitting still, and the eyes confirm this by looking around at stationary objects inside the vehicle. When the brain gets presented with conflicting information it has to decide which pieces to believe and which to discard, and in almost every case it chooses the eyes (the dominant sense for humans) as the believable source of information.
So now your vestibular system is being ignored. Not necessarily a problem, the brain ignores loads of information every minute and this should be just a temporary situation. If we have a healthy vestibular system that is functioning well, this is where the problem ends. Think of it as confidence, if somebody tells you they don’t believe you when you know you are correct, it doesn’t cause you anxiety. However if our vestibular system is not functioning at it’s best. the news that it is being ignored sparks what I can only describe as the brain’s version of imposter syndrome. To the vestibular system, it is equally likely that the information is correct but not useful, or incorrect and dangerous. This causes panic, and as this panic rises it gives rise to motion sickness.
Ok Great, But Why Nausea?
The follow up question I always get asked when talking about motion sickness is: ‘Ok, the sensory disagreement makes sense, but why would it cause nausea?’ This is pretty fair since nausea comes from the stomach, not an organ we traditionally associate with movement. The answer again might be surprising; your brain thinks it has been poisoned.
This one will take a bit of unpacking. There is a saying in neuroscience that neurons that wire together, fire together. Basically it means that parts of the brain that live next to each other usually influence each other. And as it happens, the nerve that connects balance to the brain (the vestibularcochlear nerve) is sitting right next to the nerve that connects digestion to the brain (the vagus nerve). This makes sense, as when we are exercising intensely or running from danger, the brain will switch off the digestive system in order to focus on survival. The relationship works the other way too, when the digestive system becomes completely overwhelmed, usually due to some unwelcome substance in the stomach, it can trigger dizziness in the vestibular system in order to stop us from moving around too much.
In the case of motion sickness then, the panic experienced by the vestibular system cannot be justified to the brain as a movement issue, as all systems involved in movement seem to be functioning correctly. The brain then makes the assumption that the vestibular system could be being triggered by the vagus nerve. Despite no signal coming from the stomach to confirm this, the consequences of being wrong are severe and the brain would rather not take that chance. It makes the asusmption that the signals from the vestibular system are coming from the vagus nerve, and sends the appropriate signal of nausea to deal with it.
So What Can We Do?
There are a few things that can be helpful when it comes to motion sickness. First and foremost, it is a good idea to try and sync your senses back up as much as possible. Focusing your eyes outside the vehicle will help the brain see that the motion detected by the vestibular system is genuine.
In terms of long term benefits, the best thing to do is to strengthen the vestibular system, as well as improving its communication with the eyes and the body. If you are interested in a tool that can do just that, I would recommend checking out the Neuroband, a wearable vision & balance training tool that helps to challenge & integrate the eyes, body and inner ear so they perform as a cohesive unit.
