The ‘red’ light is assumed to be a 830nm light emitting diode which projects light to the back of the retina so that the inside camera picks up the ‘red-eye’ effect which is sometimes seen in flash photos.

How do I fix my 3DS camera error?

Error Message: Error Has Occurred While Loading the Nintendo 3DS Camera Application
Press and hold the POWER Button down until the system powers off. Then power the system back on.Continue to use the system to see if the error reoccurs.General system stability can be improved by applying a System Update.

How long does a 3DS last on red?

It generally lasts around 15-30 minutes depending on whether WiFi, 3D, and other things are on.

Error Message: An Error Has Occurred. Hold Down the POWER Button.
Press and hold the POWER Button down until the system powers off (about 10 seconds), then power the system back on.General system stability can be improved by applying the latest system update.