Ever dreamt you were on a train going into a tunnel? Some people might attribute a Freudian explanation that it represents sex, while others might say you were just traveling. Since humans began dreaming, they’ve come up with interpretations about it. While there’s no one-size-fits-all dream lexicon, connecting your waking associations with the images in your dreams can lead you to fruitful psychological territory. “Most modern clinicians who work with dreams use the dream to understand what may be metaphoric thought in that person’s shorthand,” says Deirdre Barrett, Ph.D., a psychologist and author of the books The Committee of Sleep: How Artists, Scientists, and Athletes Use Dreams for Creative Problem-Solving – and How You Can Too, and Trauma and Dreams. We asked Barrett to explain 10 dream themes.