Seasickness and Scuba
“
Keep your eyes on the horizon.” It’s advice often shared with divers
who are looking a little queasy while out on the water. If you’ve tried
it, you may be able to attest to the value of that advice. But why does
it work?
Motion sickness occurs when the brain receives conflicting information
about the body’s position. There are three primary pathways through
which the brain receives positional information: the vestibular system,
eyes and proprioceptors.
1.
Vestibular system: Located in the inner ear, the components
of the vestibular system are the vestibule and the three semicircular
canals of the inner ear. The vestibular system detects angular and
vertical motion (such as pitching and rocking on a boat) and
communicates that information to the brain.
2.
Eyes: Your eyes detect visual signals and use that
information to determine the body’s spatial references. For instance,
when you look at a steady object in the distance, such as the horizon,
your eyes observe movement and signal to the brain that the body is
moving.
3.
Proprioceptors: These sensors are located in the muscles,
tendons and joints. They detect the body’s position and movement to
maintain balance. For example, if you close your eyes and extend your
wrist, you know where your hand is, even without looking, thanks to your
proprioceptors. If you are walking on a rocking boat, your
proprioceptors sense your muscles, tendons and joints moving in response
to motion and transmit that information to the brain.
If the information the brain receives from these three sources is in
conflict, you may experience symptoms of seasickness. This could occur
if you are reading a book while on a boat. Your eyes focus on the page,
which is stationary, sending the brain the message that there is no
movement. Meanwhile, your proprioceptors and vestibular system detect
the motion of the boat and communicate that information to the brain.
This inconsistency can result in motion sickness.
If you are unfortunate enough to fall victim to
mal de mar, your
face may appear pale and you may experience symptoms such as vomiting,
nausea, sweating, abdominal discomfort, vertigo, headache, fatigue or
hyperventilation.
Certain factors may increase your susceptibility to motion sickness,
including alcohol consumption, overeating, consuming rich, greasy or
spicy food, anxiety, odors (such as exhaust fumes), heat, inner ear
injury or infection, jet lag and fatigue.
Mitigate Your Risk
There are ways to help prevent motion sickness. Here are some tips you can try:
· Avoid heavy, greasy meals and alcohol, which can contribute to nausea.
· Ensure you are hydrated and well rested.
· After you have boarded, select a position on the boat where motion
is limited; typically this is near the center of the vessel and close to
the waterline.
· If possible, don’t sit near the stern as you may be exposed to exhaust fumes.
· Avoid the tower, the bow and below decks where the boat moves the
most. There is often limited ventilation below decks and only a few
portholes, depriving you of visual confirmation of movement.
· On the open water, avoid focus-intensive tasks such as reading,
writing or putting your gear together while the boat is in motion; you
may even want to put your kit together as soon as you board the boat.
· Throughout the trip, focus on a fixed point in the distance, such as
the horizon, or try closing your eyes to help reduce input of
conflicting stimuli.
· Small servings of plain, easily digestible foods like saltine crackers or bananas may help reduce symptoms of seasickness.
Medications
Some divers choose to use medications to prevent motion sickness, such
as dimenhydrinate, meclizine and scopolamine. There are two important
factors that should be taken into careful consideration: whether there
are any side effects of the medication that could impair your ability to
dive safely (such as drowsiness or confusion), and whether the
medication effectively controls your symptoms of seasickness. If you
choose to use a medication for motion sickness, it is essential to have
experience taking it many times on land or outside the context of diving
so you are more likely to be prepared for any side effects it may
cause.
As with any medication, talk to your physician before trying something
new. If you experience any symptoms while diving that could impair your
ability to complete the dive safely, it is recommended that you end the
dive without delay.
Natural Remedies
In addition to behavioral precautions and pharmaceutical prevention of
motion sickness, some divers employ alternative remedies. Ginger is
often considered nature’s anti-nausea medicine, and small portions of
carbonated, non-alcoholic beverages and crackers can also help alleviate
nausea symptoms.
Another alternative method employed by some divers is wristbands
manufactured to stimulate the Nei-Kuan pressure points using mild
electrical stimulation or simple mechanical pressure. These pressure
points are located just below the wrist joint. Some divers have found
these wrist bands an effective means of controlling nausea and
mitigating the effects of seasickness, while others have not.
Ultimately, there is no surefire cure, but if you have found a method or
combination of methods that effectively mitigates motion sickness for
you, adhere to it.
As you adapt to being onboard a boat, symptoms of seasickness tend to
subside. Finding your sea legs can take from just a few hours up to
several days. For more information,
www.Dan.org
. If you have any
questions about motion sickness, call the DAN Medical Information Line
at +1-919-684-2948.
Divers Alert Network® (DAN®) is a nonprofit organization dedicated to
the safety and health of scuba divers. DAN operates a 24-hour emergency
hotline (+1-919-684-9111) to help divers in need of medical emergency
assistance for diving or non-diving incidents.