For many of us, sleep is the sweet balm that soothes and restores us after a long day of work and play. But for those for whom sleep is elusive or otherwise troubled, the issue is far more fraught. Most people, at some point in their lives, experience difficulty falling asleep.
Why we dream is still one of the behavioral sciences' greatest unanswered questions. Researchers have offered many theories—memory consolidation, emotional regulation, threat simulation—but a unified one remains, well, a pipe dream. Nevertheless, people continue mining their nighttime reveries for clues to their inner lives, for creative insight, and even for premonitions.