Sea-sickness
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Seasickness is a form of motion sickness characterized by a feeling of nausea and, in extreme cases, vertigo experienced after spending time on a craft on water. It is typically brought on by the rocking motion of the craft, but people who are particularly vulnerable to the condition can feel seasick simply by setting foot on a boat, even if the vessel is in dry dock.
Seasickness can be a debilitating condition and it is extremely dangerous if the sufferer has an important role to carry out, such as steering a yacht through stormy seas while avoiding rocks and other hazards. It is also particularly hazardous for scuba divers who, through dehydration following vomiting, are at increased risk of decompression illness.
Cause
Human beings instinctively seek to remain upright by keeping their centre of gravity over their feet. The most important way this is achieved is by visual reference to surrounding objects, such as the horizon. Seasickness often results from the visual confusion on a moving craft, when nearby objects move with the motion of the craft. Because the lines of the masts, windows, and furniture on a ship are constantly shifting with respect to fixed references, humans can suffer a number of afflictions, especially those unaccustomed to being at sea.Sea-sickness has such a remarkable effect because both the sense of sight and touch are disturbed by the motion of a craft on water. The severity of seasickness is also influenced by the irregular pressure of the bowels against the diaphragm as they shift with the rising and falling of the ship.
Many experience similar effects while not at sea:
- in railway carriages
- in automobiles
- on swings
- while looking from a lofty precipice where known objects, being distant, are viewed under a new aspect and not so readily recognised
- while walking on a wall or roof
- while looking directly up to a roof
- while observing the stars in the zenith
- on walking into a round room, where there are no perpendicular lines of light and shade and the walls and roof are covered with an irregularly-spotted design
- on twirling round, as in waltzing
Prevention and remedy
Over-the-counter and prescription medications such as dramamine and transdermal scopolamine are readily available. Some sufferers find that wearing special wristbands also helps stave off the condition.Those suffering from seasickness who are unaccustomed to the motion of a ship often find relief by
- keeping their eyes directed to the fixed shore or horizon, where possible
- lying down on their backs and closing their eyes
- drinking any substance that is likely to temporarily diminish their senses of sight and touch
- move into a position where fresh air is blowing on their face
- sucking on crystalised ginger, sipping ginger tea or taking a capsule of ginger.
- keeping near the centre of the boat where any rocking motion is least pronounced
See also
External Links
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