Imagine for a moment that the world surrounding your screen is mostly the same, but feels slightly off. In this world, things appear suddenly with little or no context — like an emerging sound of a man yelling that starts out as a faint, ephemeral whisper before it swells louder and louder. Just as you’ve traced the voice to some guy you haven’t seen since high school, you suddenly feel as if you’re drifting upward, closer and closer to the surface of your original world. Here, in the foggy intersection between sleep and wake, you realize the other world was a dream.
But once you’re awake in this world, there’s no longer the sound of a man yelling. Did you dream it, or hallucinate it upon waking? Maybe someone was really there? As you try to decide which is the truth, your mind wanders to the last time this experience happened to you, perhaps while on vacation, and before you know it you’re immersed in a daydream full of salty ocean waves.
Judy Ford, a neuroscientist at the University of California San Francisco and the San Francisco VA Medical Center, says these kinds of experiences are common and normal while waking up, when it’s difficult to establish the boundaries of our reality. It’s especially hard because our brains are so good at creating, in a sense, alternate realities in our mind.
