Light

When Confined To Darkness, Your Brain Puts On A Light Show

If you've ever been alone in the dark for an extended period of time, you know the phenomenon: out of the darkness, an imaginary light show appears and dances around the blackness before your eyes. If you haven't had this experience, it might sound like a scene from a weird sci-fi flick. But it's a real psychological phenomenon, and it's called the prisoner's cinema.

Stars Or Phosphenes?

To explore this light show in your mind, we need to describe the phenomenon of phosphenes. Have you ever rubbed or poked your eyes and seen stars? Those bursts of light are called phosphenes, and some researchers say they're actually caused by light being produced inside your eyes. 

As Scienceline explains, "In the same way that fireflies and deep-sea creatures can glow, cells within our eyes emit biophotons, or biologically produced light particles." Your retina converts light into electrical signals, which travel through your optic nerve to your brain's visual cortex. From there, your brain decides whether these signals are real, or in your head.

Lightness In The Dark

Phosphenes can happen randomly, but they're most likely to occur when a person has been subjected to long periods without visual stimuli, like an overnight hike or a stint in solitary confinement—hence the name "prisoner's cinema." The phenomenon is also commonly reported by long-haul truck drivers and airplane pilots. Want a quick way to see your own private light show? Use a finger to place some gentle pressure on your eyelid. Who needs fireworks when you've got phosphenes?

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Key Facts In This Video

  1. Phosphenes are the result of your visual system being fooled in some form or fashion. 00:34

  2. You can produce phosphenes by passing an electrical field by your occipital lobe or placing electrodes near your optic nerve. 01:31

  3. You see stars when someone hits you on the back of your head because that stimulates the occipital lobe. 02:14

Written By
Curiosity Staff
May 22, 2017