Motion Sickness: When Your Brain Gets Confused

Motion sickness is a fairly common condition that affects many people, particularly when they are travelling in a car, boat, or plane. It can result in symptoms such as nausea, dizziness, and vomiting and can make travelling an uncomfortable experience. That queasy, dizzy feeling you get after a thrilling ride or a bumpy boat trip isn’t just an inconvenience. It’s a fascinating window into the workings of our inner ear, the incredible conductor of our sense of balance, known as the vestibular system. Understanding the vestibular system and how it works can help us understand why motion sickness occurs and how we can prevent or alleviate its symptoms.

Symptoms of Motion Sickness

Motion sickness can manifest itself in various ways, with symptoms ranging from the most common, such as nausea and vomiting, to cold sweating, pallor, headache, yawning, drowsiness, loss of appetite, increased salivation, and a desire to be left alone. These symptoms usually occur after being exposed to unfamiliar motion or an inciting event that triggers motion sickness. For most people, symptoms usually go away within 24 to 72 hours.

What Causes It

Motion sickness is usually caused by a movement that goes up and down or side to side. It can happen when you travel by air, sea, or road or when you play video games or use virtual simulators. Scientists believe that motion sickness happens because the signals that your brain gets from your eyes, inner ear, and body don’t match up. When your brain gets mixed signals, it can cause feelings of nausea and other symptoms.

The vestibular system is a network of structures located inside the inner ear that is responsible for maintaining balance, posture, and spatial orientation. It includes:

• The semicircular canals, which detect rotational movements of the head.
• The otolith organs, which detect linear acceleration and changes in position.

These structures are lined with tiny hair cells that bend in response to fluid movements, sending electrical signals to the brain that inform it about changes in the body’s position and motion.

Simply put, It’s an intricate network of fluid-filled canals and hair cells that act as motion detectors. These intricate hairs sway and bend with every tilt, turn, and acceleration you experience, sending electrical signals to your brain informing it about your body’s position and movement. Think of it as your body’s internal GPS, constantly updating your location and direction. But things get interesting when this system encounters conflicting information.

When a person is in motion, the vestibular system receives signals about the body’s movement and position. These signals are integrated with visual cues from the eyes and proprioceptive information from the muscles and joints to create a coherent sense of space and movement. However, when the signals from the different sensory systems conflict with each other, it can result in motion sickness.

For example, when a person is on a boat that is moving up and down with the waves, the inner ear detects the motion and sends signals to the brain that the body is moving. However, the eyes may see a stationary object, such as the horizon, which can create a mismatch between the visual and vestibular signals. This conflict causes the brain to become confused and results in symptoms such as nausea and dizziness.

Another example is when you’re reading a book on a ship, your visual system sends signals suggesting you’re still while your inner ears scream, “We’re bouncing all over the place!” This conflicting information throws your brain into a loop, resulting in the unpleasant symptoms of seasickness.

This sensory mismatch creates confusion in your brain. Unable to reconcile the conflicting information, your body interprets this disorientation as a potential threat, like being poisoned. The “fight-or-flight” response kicks in, leading to the classic symptoms of motion sickness: nausea, dizziness, sweating, and that unsettling feeling like the room is spinning.

Fun facts:

• Hippocrates was the first to describe motion sickness symptoms, and he wrote that “sailing on the sea proves that motion disorders the body.” The term nausea, which is the primary symptom of motion sickness, comes from the Greek word for ship, naus, as it is commonly associated with sea travel.
• Motion sickness doesn’t just impact humans, but also certain animals like fish. It’s quite ironic to think that a fish, accustomed to life in the sea, could potentially experience seasickness. That’s why it’s more appropriate to say they experience motion sickness rather than sea sickness since the sea is their natural habitat.

Risk Factors

Certain factors can make a person more likely to experience motion sickness, such as:

• Gender: Women are more likely to get motion sickness than men.
• Age: Motion sickness typically starts around age 6 and peaks at age 9. This is potentially because their brains are still developing the ability to smoothly integrate different sensory inputs. It tends to decrease during the teenage years due to habituation. Elderly people are the least likely to experience motion sickness.
• Fitness level: Some studies suggest that people with high levels of aerobic fitness may be more susceptible to motion sickness due to a more reactive autonomic system.
• Medical conditions: People with vertigo, vestibular pathology, Meniere’s disease, and migraines are more likely to experience motion sickness.
• Hormones: Fluctuations in hormones during pregnancy and the menstrual cycle can increase the likelihood of experiencing motion sickness.

Prevention and Treatment

Behavioural techniques:

To prevent motion sickness, there are some tricks you can try. For a short-term solution, you can try the following:

• Individuals who are susceptible should refrain from consuming heavy meals, alcohol, caffeine, foods that are high in histamine content (such as cheese, tuna or salami), or a large quantity of liquid before travelling.
• Avoid reading or watching a video screen while the vehicle is moving, as this can exacerbate the sensory mismatch between the eyes and the inner ear.
• Change your posture and reduce head and body movements as much as you can.
• Focus on a fixed point on the horizon to help you feel more stable.
• Avoid travelling in bad weather or when the ride is bumpy.
• Sit in the front seat or drive the car yourself.
• Breathe slowly and steadily.
• Listen to music you enjoy.
• Don’t smoke.

The most effective long-term solution is to get used to the motion over time, which is called habituation. It’s better than taking medicine because it doesn’t cause side effects such as drowsiness or blurred vision.

Medications:

Medicines to treat motion sickness may not work completely and can have side effects. They work best when taken before symptoms start or as soon as they begin. People should try the medicines in a safe place before using them while travelling or working. There are three types of these medicines – anticholinergics (the most common drug of which is scopolamine), antihistamines, and sympathomimetics.

It’s worth mentioning that motion sickness is not a serious medical condition but rather a natural reaction to actual or virtual motion that mostly happens to people with a healthy vestibular system. People who have lost their vestibular system function due to illness or surgery usually don’t experience motion sickness. So next time you get this feeling, rest assured that your vestibular system is just doing its job, but it may have just gone too far.

In conclusion, motion sickness is a pretty common condition that results from a conflict between the signals sent by the inner ear and the eyes. Understanding the vestibular system and taking steps to prevent motion sickness can help make travelling a more enjoyable and comfortable experience. By focusing on a fixed point on the horizon, staying stable, and avoiding overstimulation, we can reduce the risk of motion sickness and enjoy our travels without discomfort.

References:

• Motion Sickness.
• Motion sickness: an overview.
• Motion Sickness: Current Knowledge and Recent Advance.