Motion sickness can ruin a great vacation or road trip adventure.  According to Popular Science, it hits when we are at rest inside a vehicle in motion, making us carsick, seasick or airsick, or sick on an amusement park ride.

The two most common signals of motion sickness are nausea and vomiting. Other symptoms include feeling flushed, dizzy, or disoriented, headaches, loss of appetite, salivating and cold sweats.

Experts postulate there are two causes of motion sickness. One theory is that as we lose control over our posture, as in a rocking boat, this postural instability makes us sick. The second, more widely accepted theory, is that our sensory symptoms and our brain aren’t in sync. For example, when we turn our heads, our eyes register the movement giving visual clues but our muscles, joints, and vestibular system including the brain and inner ear, must also be in alignment.

If our bodies’ sensations match each other — if the eyes and the vestibular system line up — and our minds’ expectations follow, we feel fine. If they are slightly off, that may be fine, too. But when there are big differences in how they all sync up, that’s when motion sickness sets in.

John Golding, a professor in social sciences at the University of Westminster, has been studying motion sickness for decades and he says this sensory conflict may have an evolutionary explanation. Golding proposes the “toxin theory” where “what we call motion sickness is simply the aberrant elicitation of a very ancient defense reflex.” In other words, our dizzy brains think we’re being poisoned and force us to puke to get rid of the offending substance.

Golding says that some people are more prone to motion sickness than others. People who have frequent migraines are more likely to experience illness. Babies rarely suffer motion sickness, but the condition peaks at age eight and diminishes into adulthood. However, visually induced motion sickness (VIMS) may be worse for those over the age of 65, says Popular Science.

The Centers for Disease Control and Prevention (CDC) suggests that you avoid situations that cause motion sickness, but that isn’t always possible when traveling. The following strategies can help you avoid or lessen motion sickness:

• Sit in the front of a car or bus.

• Choose a window seat on flights and trains.

• If possible, try lying down, shutting your eyes, sleeping, or looking at the horizon.

• Stay hydrated by drinking water, and limit alcohol and caffeinated beverages.

• Eat small amounts of food frequently.

• Avoid smoking. Even stopping for a short period of time helps.

• Try and distract yourself with activities, such as listening to music.

• Use flavored lozenges, such as ginger candy.

The CDC adds that medicines can be used to prevent or treat motion sickness, but they may cause drowsiness as a side effect. Commonly used medicines are diphenhydramine (Benadryl), dimenhydrinate (Dramamine), and scopolamine.