Motion sickness (seasickness, or mal de mer) is a common annoying, and sometimes disabling, problem for boaters and divers. Those who have suffered the malady while on a rough voyage, a fishing trip in high seas, or even a routine crossing complicated by a sudden squall or the odor of diesel exhaust can attest to the discomfort. This article will explain the phenomenon of motion sickness and provide you with the latest tips for avoiding and/or managing seasickness while diving.
What Causes Motion Sickness?
Seasickness is a complex phenomenon that involves the cerebellum (the part of the brain that controls, among other things, balance), vestibular system (labyrinth of the inner ear that plays a major role in the control of equilibrium), the nerve connections between the eyes and the inner ear, and the gastrointestinal tract. It is made worse by alcohol ingestion, emotional upset, noxious odors (e.g., boat exhaust fumes), and inner ear injury or infection. Motion sickness can be induced in a person who is not moving by having him or her watch an image of changing motion, such as a car chase or roller coaster ride. The special effects in some movies, particularly a large format like IMAX, can make viewers dizzy or even mildly motion sick. Most persons adapt to real motion after a few days, but may require treatment until they are adjusted to the environment.
Signs and symptoms of seasickness include a sensation of dizziness or spinning, a sensation of falling, pale skin color, sweating, nausea, headache, drowsiness, weakness, yawning and increased salivation. Vomiting may provide temporary relief, but recovery doesn’t occur until the inner ear labyrinth acclimates to motion or you are able to intervene with an anti-motion sickness device or medication. Persons who suffer from prolonged seasickness become dehydrated and exhausted. In extreme cases, seasick crews have abandoned their ships and claimed to have lost their will to live.
What New Remedies are Available?
Fortunately, there is a new nondrug remedy that may offer significant relief from the misery of motion sickness. The ReliefBand (Woodside Biomedical of Carlsbad, California, ph. (760) 804-6900) is advertised to relieve nausea and vomiting with gentle, noninvasive stimulation on the underside of the wrist. It can be used before or after symptoms begin, carries no restrictions on food, beverages, or the use of medications, and has no druglike side effects. The device looks like a wristwatch. The Adventurer model contains a battery-powered electrical stimulator that is easily adjustable for five different stimulation levels. The device is positioned over the P6 acupuncture site (the Neiguan, or Nei Kuan, point on the pericardial meridian). This is two fingerbreadths toward the heart from the wrist joint between the two prominent finger flexor tendons. The underside of the watch shows two gold-plated electrodes that contact the skin, to which the user has applied a gel to improve the transfer of the electrical pulsations. When the device is turned on, a pulse is generated every four seconds, and the user feels the episodic tingling sensation. While it is not known precisely why the device works, it is theorized that the electrical signal transmitted via the median nerve in the wrist interrupts the nausea and vomiting messages that are transmitted between the brain and the stomach. This is not unreasonable, given what we are continuing to learn about the benefits of acupuncture. For instance, it was recently reported that children who received forearm acupuncture after surgery were significantly less likely to feel nauseated or to vomit than untreated children. Other studies have found acupuncture to be as effective or better than anti-nausea drugs in postoperative patients, and also noted anti-pain effects.
There are sufficient scientific data to support the use of this device that the Food and Drug Administration has approved the ReliefBand for treatment (via prescription from a physician) for nausea and vomiting associated with pregnancy, chemotherapy, and as an adjunct to anti-vomiting medications used after surgery. The only side effect associated with use of the device is irritation where the electrodes contact the skin, which rarely occurs. This is easily managed by moving the device to the other wrist.
The ReliefBand is water-resistant (splash and rain), but not intended to be worn when actually swimming or diving. I suffer occasionally from carsickness and also from motion sickness when I’m on a boat in bouncy waters. I’ve used the device in both settings successfully, and agree with the recommendations that it requires a high enough setting for a person to feel the tingling in order to obtain relief. The sensation is quite noticeable, but not painful or unpleasant. It’s definitely better than feeling drowsy and/or seasick.
More Than Motion Sickness
Headache, ringing in the ears, weakness in an arm or leg, difficulty with speech, difficulty swallowing, decreased vision, or palpitations are not features of motion sickness and should raise suspicion for another cause of dizziness. If any of these occur, particularly if the seas are not particularly rough and no one else is suffering, the victim should seek medical attention. Similarly, if the symptoms occur after a dive, one must consider the possibility of central nervous system decompression sickness (bends) or arterial gas embolism.
Finally, don’t try to cure serious motion sickness by putting on your dive gear and heading underwater. Mild nausea attributable to seasickness may disappear when you get under the surface (and the objectionable motion ceases), but it is safer to remain topside than risk vomiting underwater.