Dark adaptation and red light?

Put two or three layers of red cellophane over the flashlight for the best results. Turn off any lights you have control of -- the less light the better. Try not to look at any white lights -- better still, locate your chair so that neighbours' lights are blocked by fences or other obstacles. Yes, you really should not look at any white light. Complete dark adaptation takes 15 to 20 minutes. If there is much light about, you may _never_ become dark adapted.