Q. What causes motion sickness?

Many people including me suffer nausea when traveling by boat, car or airplane. It also happens on rides in amusement parks and playgrounds. The symptoms of motion sickness are caused by conflicting messages arriving at the central nervous system.Different parts of your body let your brain know where you are and what you're doing. The inner ears let you know if you're turning, or moving forward-backward, side-to-side, and up-and-down.The eyes also monitor the directions of motion and where the body is in space, such as upside down. Skin pressure receptors tell you what part of the body is touching the ground. The muscle and joint sensory receptors tell what parts of the body are moving.If all the signals tell the same story, there are no problems. However, suppose you're below deck in a heaving sea. Your body is getting information that the boat is moving violently. But your eyes see the unmoving walls of your cabin.If you are susceptible to motion sickness, this below-deck scenario is almost guaranteed to make you look for a porthole to get rid of your last meal.How about the example of reading in the car? Well, your body is picking up all kinds of cues that you're in motion, but your eyes see only the unmoving pages of your book.Here are some tips to avoid motion sickness:Always ride where your eyes will see the same motion that your body senses. For example, sit in the front seat of the car and look out the windshield to distant scenery; don't stare at the rapidly passing telephone poles outside the passenger window. I prefer driving so I am forced to look straight ahead.If you're on a boat, go up on deck and watch the horizon. Request a cabin in the forward or middle of the ship, or on the upper deck.On an airplane, sit by the window and look outside. Also, choose a seat over the wings where there is the least motion. Direct the air vent at your face.On a train, take a seat near the front and next to a window. Face forward.Minimize head movement.Avoid strong odors and spicy or greasy foods immediately before and during your travel. Don't overeat.Don't smoke or sit near smokers.Before your travel begins, take motion sickness medicine recommended by your physician. There are over-the-counter drugs. There is also prescription medicine in an adhesive patch or in oral form.There are other treatments for motion sickness that may benefit some people, but they have not been proven to be consistently effective. High levels of ginger have helped some.There's an acupuncture point of the wrist that provides relief of nausea during pregnancy and after chemotherapy, but there is contradictory evidence about its effectiveness in treating motion sickness.The Times News, Inc., and affiliates (Times News) do not endorse or recommend any medical products, processes, or services or provide medical advice. The views of the author do not necessarily state or reflect those of the Times News. The article content is not intended as a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician, or other qualified health provider with any questions you may have regarding a medical condition.