Why we dream is an age-old question, one that now has a new potential explanation. A new theory posits that dreaming may be “a strange lovechild of brain plasticity and the rotation of the planet.” The idea is that since humans live in the dark half the time, their visual systems (which aren’t as useful in the dark) need to protect their space in the brain against the encroachment of other senses—and do so by creating visual images while we sleep. It’s a fascinating new angle on the purpose of dreaming.

Learn more here, on Time magazine: “Why Do We Dream? A New Theory on How It Protects Our Brains”