Experiment a little on small scale with the paint you use and color of lights. Definitely make sure that all your lights are the exact same color of blue and red - no variations. I would highly recommend LEDs. Depending on your budget, to help keep more of a realistic lighting look for a sanitarium, you could use dim white light then flip on UV light that will expose the hidden images. You would paint them with special clear paint that is revealed only under UV light.
Here's a vid that may help you: