The phenomenon you're describing, seeing a pulsing bright light when you close your eyes, is known as the "phosphene" effect. Phosphenes are the subjective sensations of light that can be perceived in the absence of external visual stimuli.
When you close your eyes, your brain is still active and continues to process signals from the visual system. In the absence of visual input, the brain can generate its own signals, resulting in the perception of light. There are a few possible explanations for the pulsing or flickering nature of the light you see:
Mechanical Pressure: Applying slight pressure to the eyeballs by closing your eyelids can stimulate the cells in the retina, causing them to generate electrical signals. This mechanical stimulation can lead to the perception of flickering or pulsing light.
Neural Activity: The visual cortex, which is responsible for processing visual information, remains active even when there is no external light entering the eyes. The neurons in the visual cortex can generate spontaneous neural activity, which can be perceived as flickering light.
Phosphene Induction: Phosphenes can also be induced by other factors such as changes in blood flow, electrical stimulation, or random firing of neurons in the visual system. These inductions can lead to the perception of pulsing or flickering light.
It's worth noting that the specific patterns and colors of the phosphenes can vary from person to person. Some individuals may see simple flashes or dots of light, while others may perceive more complex patterns or colors.
If you find the phenomenon of seeing pulsing bright lights when you close your eyes persistent or accompanied by other concerning symptoms, it is advisable to consult with a medical professional for further evaluation.