Mind, Body & Heart: All you need to know about... Researchers from Cornell University in the US found that new memories are being replayed and consolidated when the pupil is contracted during a substage of non-REM sleep. And when the pupil is dilated, the process repeats for older memories. Researchers from Cornell University in the US found that new memories are being replayed and consolidated when the pupil is contracted during a substage of non-REM sleep. And when the pupil is dilated, the process repeats for older memories.