Why do our eyes flutter about during rapid eye movement (REM) sleep? To keep track of the actions and events in our dreams, says a study in the June issue of Brain. Researchers at Pitié-Salpêtrière Hospital in Paris studied people who have a disorder that makes them act out their dreams (but whose eye movements have been shown not to differ from healthy sleepers). Using electrodes to record eye movements and cameras to capture nighttime motions, the researchers found that where participants were looking and what they were doing synchronized 90 percent of the time. A subject dreaming about climbing a ladder, for instance, repeatedly gazed up and down to check his progress.