Could dreams be memories from another timeline?

It’s an intriguing sci-fi idea, but there is no scientific evidence that dreams are memories from another timeline.

From neuroscience, dreams are generally understood as products of brain activity during sleep, especially REM sleep. They often weave together memories, emotions, fears, and recent experiences into strange or vivid scenarios. Researchers also study possible roles for dreaming in memory consolidation, emotional regulation, and other sleep-related brain functions.

The Many-Worlds Interpretation of quantum mechanics is sometimes mentioned in this context because it describes the universe as branching into different outcomes. But that is a theoretical interpretation, not evidence that dreams access other timelines. In Many-Worlds, separate branches are effectively decoupled, so there is no known mechanism for information to pass between them and appear in dreams.

So the most grounded answer is: dreams are best explained by your own brain, not by memories from another timeline.