What's the purpose of dreaming?

Breakthroughs, discoveries, and DIY tips sent every weekday. As with many mysteries of the mind, science doesn't have one neat answer. "You'll get as many answers to the question'What is the purpose of dreaming?' as there are dream psychologists," says Deirdre Barrett, dream researcher at Harvard University and author of The Committee of Sleep. According to Austrian neurologist and founder of psychoanalysis Sigmund Freud, dreams offered vital clues to unresolved conflicts buried deep within our psyche. But Freud's theory, introduced in his 1899 book The Interpretation of Dreams, sparked plenty of controversy.