TRAVEL SICKNESS

Some people can cope effortlessly with the roughest sea or air journey - others feel ill before the aircraft has taken off or the ship has even left the dock. The chances of travel sickness can be minimized, however, by taking sensible precautions

The main cause of travel sickness is motion of the vehicle in while travelling - the rolling and tossing of the ship, the swaying of a car as it rounds a series of bends, the rhythmic movements of a train - so that travel sickness is sometimes called ‘motion sickness’. However, psychological factors can also be important: the mere thought of a boat journey can make some people feel queasy, while fear of flying is a frequent cause of air-sickness.

WHY DOES IT HAPPEN ?

Travel sickness results from an imbalance of information reaching the brain from the various sense organs concerned with movement. One of the most important of these is the balance organ in the inner ear, which contains three fluid-filled canals (the semicircular canals). These are like three spirit levels placed at right angles to each other; head movement in any direction causes movement of the fluid in one or more of the canals. A volley of nerve impulse is then sent to the brain via the vestibulochlear nerve. At the same time, the brain receives information about movement from a number of other sources, particularly the eyes. If the brain’s central computer can make sense of these various pieces of information, no harm will result. If, however, the information coming from the inner ear or the eyes is confusing or conflicting, signals are sent to a part of the brain called the vomiting centre which triggers off both the feeling of nausea and the physical act of vomiting.

One way of understanding why this happens is to consider the difference between a cyclist travelling along a road, the driver of a following car and someone sitting in the back of the car reading a book. When the cyclist rounds a bend, both his eyes and inner ear send the same information about the movement to his brain, so no confusion results. The same applies to the driver of the car. The passenger in the back seat, however, senses the movement only with his inner ear; the car seat and the book in front of him do not move in relation to his eyes. The brain cannot make sense of this and sooner or later the passenger may feel nauseous and may want to vomit.

The same applies to someone sitting in the lounge of a cross channel ferry during a rough voyage. The more violent the movements of the vehicle - whether car, boat, train, or aircraft - the more likely the brain is to be confused and the vomiting centre triggered off. People who have been travel sick several times may develop a psychological association between a particular form of travel and the feeling of being unwell; they unconsciously expect to be sick even before the journey has started. Psychologists calls this type of reaction a ‘conditioned reflex’. It accounts for the fact that some people feel seasick before the boat has even left the dock.

SYMPTOMS

The symptoms of travel sickness, are different from person to person, although a particular individual always experiences the same symptoms and in the same order. Giddiness, nausea and vomiting are the most obvious, but other common ones include headaches, drowsiness, increased breathing efforts, yawning and pallid skin complexion.

Vomiting is a useful reflex if one has swallowed something poisonous or noxious, but its function in motion sickness is something of a mystery. Probably it is a purely accidental feature of human physiology.

DRUGS WHICH CAN HELP

Fortunately there is a wide variety of travel sickness pills available under many brand names and each contains a particular drug effective against motion sickness. Some of the drugs which are short-acting, being effective for only three or four hours, are more suitable for short journeys; others are longer acting and are more suitable for prolonged journeys. Most can be bought over the counter at the chemist's, but anyone with a recurrent problem with travel sickness should consult a doctor.

Different travel sickness pills have different effects on different people, so it may be necessary to try out two or three brands before one is found that is suitable and effective. Once this has been found it is best to stick to it if possible.

Most of the drugs act on the central nervous system, damping down nerve activity either in the ear's balance organ or in the vomiting centre itself. Simply taking them probably also has a psychologically beneficial effect: if one expects a drug to work, it often will, whether or not it has any real pharmacological action.

Most travel sickness pills have the side- effect of drowsiness, so are unsuitable for car drivers. It is a good idea to try the pills it in the safety of your own home some days before the journey, and if drowsiness is a real problem, ask your doctor to prescribe or recommend an alternative drug. Drowsiness can also, of course, be a useful side-effect, especially for during long car journeys.

Children do seem to be much more susceptible to travel sickness, the ages at which they are particularly vulnerable being between four and 12. By the time they reach their teens, most children have adapted to travel and know they should avoid such activities as reading in a moving car. Remember that children need a far smaller dose of travel pills than adults -if they don't work, do not be tempted to increase the dose. Ask your doctor to recommend some alternative drug suitable for children.

The doses and duration of action vary from drug to drug, and you should adhere strictly to the instructions supplied with the pills - take care not to exceed the maximum stated dose. Alcohol mixes very badly with these drugs and can produce a severe or dangerous degree of sedation.

Taking a pill when one already feels sick is usually of little use. The drug may be expelled immediately when one vomits, and in any case cannot reach its site of absorption into the body - the intestines - because the sphincter at the base of the stomach has sealed off. Sucking the pill may, however, have a useful effect if it does not taste too bad. In this case the drug is absorbed into the bloodstream through the lining underneath the tongue.

AVOIDING TRAVEL SICKNESS

The chances of travel sickness can be minimized in a number of ways. On a ship, the best idea is to stay on deck and scan the horizon. In this way, the eyes receive a constant flow of information about the ship's movements which compensates for the information coming from the ear's balance organ. Leaning over the rails and looking at the sea itself is not such a good idea - the constant see-saw motion of the waves passing across one's visual field is likely to be just a bit more than the brain can cope with.

Similarly, as a car passenger, it is best to focus one's attention on objects in the far distance. Reading a book or watching a hedge whizz by through a side window are more likely to make one feel nauseous. Children in the back seat should be seated high enough for them to have a good view. Having a window open to allow fresh air to circulate is also an extremely good idea, especially if one of the car's occupants is smoking.

Having some control over one's movements, such as driving a car or taking the tiller of a dinghy or motor boat, is another method of avoiding sickness. Occupying one's mind also seems to help: 'spotting' games are particularly useful for long car or coach journeys with children.

Travelling on either an empty or an overfull stomach is best avoided. Frequent small snacks are a better idea and rich or fatty foods should be avoided. Alcohol should be avoided, particularly by anyone who has taken a travel pill. Heavy drinking the night before to take your mind off the impending journey is not to be recommended - in fact, a hangover will greatly increase the chances of experiencing travel sickness.

Much can be done to reduce the stresses of a journey by being well prepared in advance, rather than packing in a hurry at the last moment. Anyone who finds the prospect of flying very worrying should consult a doctor, who may be prepared to prescribe a small quantity of a tranquillizing drug to be taken before the flight begins. This would have the effect of just taking the edge off any tension the person may be feeling early on in the flight.

AVOIDING CAR SICKNESS IN CHILDREN

Until they are about 12 years old many children are very susceptible to car sickness. Here are some tips which may make them more comfortable while they are travelling:

It is not safe for young children to travel in the front of the car but you can enable them to have a clear view of the road ahead by strapping them securely into a safety seat slightly higher than the level of the ordinary rear passenger seat. Discourage older children from reading while the car is moving: the confusing signals sent to the brain may quickly bring on feelings of nausea.

Keeping their minds occupied is important, however, so games such as 'I-Spy', or counting the number of passing red cars can serve the dual purpose of whiling away the time on what might seem a journey and keeping their attention fixed on the road ahead.