“Mal de débarquement syndrome (MdDS) — which means, “sickness of disembarkation” — is a rare condition that makes you feel like you’re moving, even when you’re not. “Disembarkation” is a word to describe getting off of a boat or aircraft. This can cause a change in your stability or balance.

MdDS commonly occurs after boating or sea travel, though it can happen after air travel, extended land travel and even sleeping on water beds. In some cases, MdDS can occur after non-motion events (like surgery or childbirth), or for no known reason (spontaneous mal de débarquement syndrome).”

Cleveland Clinic (https://my.clevelandclinic.org/health/diseases/24796-mal-de-debarquement-syndrome-mdds)