I have a light on my defense shotgun. It has a momentary switch, to me that is a required piece of equipment. You may give yourself away using a light just as you may give yourself away making noise moving through your house. You should know your house better than anyone else, use that knowledge to your advantage.
One technique for using supplemental lights in home defense/self defense situations is [B]indirect[B lighting. This is where you use the peripheral part of the beam coming from your light to guide you. There are several positives for this technique. First, if you avoid looking at the most brightly lit area you affect your night vision capability less. Secondly, you can disguise where you are if someone is observing the light beam. The process looks like this: use the light only intermittently, do a quick spot check of corners, furniture, etc., where a person may seek to avoid being seen, you should know these places, it is your house! When using the light only turn it on for a few seconds at most, just enough time to get a handle on where you are, obstacles that may be there, such as shoes left out, kid's toys, etc., and to spot things that are abnormal, curtains pulled away, broken glass, door ajar, wet or muddy tracks on the floor. You can move from place of cover/concealment to another place in this fashion without illuming youself and your direction of travel. Shine the light to the side or even somewhat behind you if it has a broad enough beam. It doesn't have to be exceptionally bright unless you have extreme difficulties with night vision. This method of intermittent lighting, varying the spot the light is shining on and varying the beam's angle can disguise where you are to someone observing the light. When or if you come upon a target you have the ability to positively identify it, and make a good hit.
Join the NRA! Stop the Brady madness!