My seven year old daughter occasionally gets carsick, but any time we take a trip for an extended period of time, two hours to eight hours in the car, she always throws up in her sleep that night. I can't figure out why she has this delayed reaction to riding in the car. We used to think it was related to elevation as it would happen when we went camping in the sierras, over the Siskiyou Mountains in Oregon, or over the grapevine in Southern California. But last week it happened when we took a six hour round trip at sea level. Last night we went to the harness races and she rode backward in the lead car and around the track, and then she threw up in her sleep hours later. Have you ever heard of this?