Why do i see bright purple light with eyes closed?

Afterimage: This color is generated by the retina as it changes the level of current sent to the brain with the change of light signal.

Afterimage: Groups of receptors in the retina modify the signal they send to the brain when looking at the same image for a while. They may even send an opposite signal as they balance the inputs for maximum vision. Looking at a yellow light will often cause a purple afterimage for a few minutes. It is harmless. Enjoy the show.

After-image: It is not uncommon if you have been staring at a computer screen for periods of time to see a purple after-image when you close your eyes. Similarly, if you have been outside and looking in the direction of the sun that you will see an after-image. Almost any light source can generate such an after-image and the after image will be brighter with brighter lights and longer viewing times.