Brain waves in REM sleep help store memories

Brain waves during REM sleep solidify memories in mice, scientists report in the May 13 Science.

Scientists suspected that the eye-twitchy, dream-packed slumber known as rapid eye movement sleep was important for memory. But REM sleep’s influence on memory has been hard to study, in part because scientists often resorted to waking people or animals up — a stressful experience that might influence memory in different ways.