On simulators and on drops, closing your eyes is actually not as good as looking down at your body. Doing that stabilizes what you are looking at, because your eyes will then be moving exactly with the rest of you, and your horizon will be constant. (I don't mean look at your hand. Drop your chin to your chest and focus on a small part of your lap, then keep your eyes on that part of your body the entire time.)
Quite a few years ago, I discovered that looking through a viewfinder whilst on rides has the same effect; it keeps the horizon in line with your eyes. Found this out trying to take a photo of my eldest on Dumbo, and it has worked every since. Always use a strong wrist strap on the camera in case you lose your grip on it; you don't want to bean anyone! (And of course, don't do it on coasters where holding anything in your hands during the ride is prohibited.)