CONQUERING SEA SICKNESS

There’s nothing quite like the thrill of being on a boat in the open sea—the fresh air, the wind in your hair, and… oh wait, the sudden urge to vomit. Sea sickness has existed for thousands of years; our ancestors endured the discomfort and humiliation of sea sickness. Even the great Charles Darwin was afflicted by it.

Scientists generally agree the best defence against sea sickness is the ability to adapt to the motion of a boat or a ship — this is also known as getting your ‘sea legs’. But there is debate about how we do this. According to one school of thought, it’s about your brain learning how to predict body movement in a new environment, but others argue that it’s about learning how to maintain an upright posture.

“Balancing on two legs is an art,” explains Dr. Jelte Bos from the Dutch Organisation for Applied Scientific Research. When you start to lose balance, your eyes, inner ears, and other sensory systems alert your brain, instructing your muscles and joints to act to keep you upright. However, there’s a limit to how quickly our nerves can transmit information to and from the brain, so our brains must develop the ability to predict how our movements affect our balance, Dr. Bos said.

This predictive ability develops when we are toddlers but typically happens on solid ground. Boats, however, move in much more complex ways. Boats don’t just pitch and roll but also yaw, sway, surge, and — aptly — heave. Each boat trip is unique, influenced by the sea, weather, and the type of vessel. Cruise ships are generally more stable than smaller boats.

Until your brain adapts to the specific rhythm of the boat’s movement, it relies on the balance it learned on land. This creates a mismatch between your brain’s expectations and what your senses tell you. Once your brain adjusts to the boat’s motion, it aligns its expectations with what your senses experience voilà — you find your balance, or as they say, your “sea legs.”

Dr. Bos explained that his theory sheds light on why passengers, rather than drivers, are more prone to motion sickness. Since the driver is in control and can anticipate how sharply they’ll turn, their brain is better equipped to predict their movement. The passenger, however, is at the mercy of the driver’s actions and has a more challenging time predicting the motion, making them more susceptible to car sickness.

On the other hand, Dr. Tom Stoffregen, a human movement science expert at the University of Minnesota, suggests that the primary cause of sea sickness is how we sway. Just as people vary in their ability to learn sports like tennis or ice skating, they also differ in how well they adapt to the motion of a ship, Dr. Stoffregen explained. He said overcoming sea sickness involves unconscious trial and error with different muscle and joint movements to maintain postural stability and balance. His research has pinpointed several factors that can help with this.

One key factor is looking at the horizon, a tip mariners have passed down for ages. Another is standing with your legs farther apart. Dr. Stoffregen noted that most people get their sea legs within about 36 hours of leaving shore, although some may take longer.

His research also found that how someone sways on land before embarking on the journey can predict their likelihood of getting seasick. Interestingly, women are more likely to experience sea sickness than men, possibly due to differences in body shape and weight distribution, which affect how they sway, Dr. Stoffregen said.

Bottom line: Keep standing!

We now understand that sea sickness occurs when our senses of sight, balance, and movement send conflicting messages to the brain. In response, the brain sends out a cascade of stress-related hormones, which can lead to a highly unpleasant combination of nausea, vomiting, cold sweats, anxiety, and vertigo!