Motion sickness
Whenever we move; walk, run, swim and so on, the brain is informed by several sensors including the eyes, muscles and joint sensors and most importantly, the vestibular system. The vestibular system is found in the inner part of the ear and is made up of semicircular canals with fluids that move to indicate the direction of our movements.
In the brain is a part called area postrema that is responsible for inducing nausea and vomiting. When we take in any poisonous substance, this part of the brain detects it and causes us to vomit to eliminate the poison ingested.
When the brain receives contradictory information from the eye and the inner ear with respect to the body's movement, it gets confused and thinks it is some form of hallucination due to a poison and causes the area postrema to induce nausea and vomiting. This is known as motion sickness or kinetosis.
Motion sickness is a common problem in people travelling by car, train, airplanes and especially boats. It can also occur with some amusement park games and even with motion simulation games.
When travelling on a winding or rough road, the inner ear records more motion than the eye sees. When one is down below a ship or boat, the inner ear records a lot of motion while the eyes see no motion at all. When playing some computer games and using driving or flying simulations, the eye sees a lot of motion but the inner ear records none. All these discrepancies in the information the brain receives from the eye and the middle ear confuse the brain and cause motion sickness.
Motion sickness can start suddenly, with a queasy feeling (feeling ill in the stomach) and cold sweats. It can then lead to nausea, dizziness and vomiting. Other symptoms include headache, increased salivation, fast shallow breathing and fatigue.
There are some factors that promote motion sickness. Children aged 2 - 12 are most likely to get motion sickness. The sick and people with heightened level of fear or anxiety also easily get motion sickness. If the vehicle has poor ventilation or if you sit in the back seat or where you cannot see outside the window or if you read in the car, you can easily experience motion sickness.
Although motion sickness usually goes away after the motion stops and causes no lasting harm, it can be devastating for people whose jobs involve constant movement, such as a flight attendant, pilot, astronaut, or ship crew member.
People who do not travel often may get used to movement during a trip lasting several days. Even those who travel often may find that symptoms improve as they are frequently exposed to motion.
To prevent motion sickness, the following are helpful. Simply look out of the window of the moving vehicle and if in a boat gaze toward the horizon in the direction of travel. Taking seat in front of the vehicle is also helpful.
In the night, or in a ship without windows, it is helpful to simply close one's eyes, or if possible, take a nap. This resolves the input conflict between the eyes and the inner ear. Napping also helps prevent psychogenic effects (i.e. the effect of sickness being magnified by thinking about it).
Cool, fresh air can also relieve motion sickness slightly, so open the window and let the air in or turn the air flow vent onto your face. Eating dry crackers and drinking carbonated drink (such as ginger ale) help some people avoid nausea.
Slow deep breathing helps to reduce motion sickness. In a study of 46 people with motion sickness, those who took slow, deep breaths had a significant reduction in symptoms of motion sickness compared to those who breathed normally or counted their breaths. Involuntary rapid and shallow breathing often exacerbates symptoms of motion sickness. Deliberate breathing helps reduce anxiety associated with motion sickness.
If travelling sickness is a problem for you and the above do not help, you can see your doctor for some medication. Medications for motion sickness may cause drowsiness and impair judgment. Pilots, ship crew members, or anyone operating heavy equipment or driving a car should not take them.
Some of the medication work on the area prostrema and stop the processes leading to motion sickness. Some also work to dampen the inner ear sensors.
Depending on the medication, they are to be taken 2 – 8 hours before travelling.
Mind-body therapies are also helpful in minimising the symptoms of motion sickness. In a study of 55 pilots who had to stop flying due to motion sickness, 76% of them successfully overcame their motion sickness and were able to return to work after participating in a biofeedback training and relaxation program. The pilots were exposed to a situation causing motion sickness (sitting in a tilting, rotating chair) while biofeedback instruments recorded skin temperature and changes in muscle tension. While in the chair, the pilots used relaxation techniques, such as deep muscle relaxation and mental imagery. Over time, the pilots became used to the rotating chair and no longer felt sick as they learned to relax.
Some studies suggest that acupressure may help reduce symptoms of motion sickness in the same way as acupuncture, although the evidence is not clear. The acupuncture point known as Pericardium 6, traditionally has been said to help relieve nausea. It is located on the inside of the wrist, about the length of 2 fingernails up the arm from the centre of the wrist crease. Many travel stores sell wrist bands with built in buttons designed to apply acupressure to this point.
Source: Dr. Emmanuel Kwesi Coomson Regional Hospital, Koforidua kcoomson@yahoo.com - Ghanaian Chronicle
