The strobe light as personal defense is a relatively new idea, but one that is growing in popularity. A growing number of police are turning to tactical flashlights with strobe function for a non-lethal and painless method of subduing suspects, and even the military is researching the effectiveness of strobe lights on the battlefield.
At this point in in its advancement, however, the strobe light is most likely at its greatest advantage in the hands of civilians, who are less likely to carry dedicated weapons. And today's tactical LED flashlights are extremely bright. Where grocery store, utility drawer flashlights are typically about 8 lumens in brightness, tactical flashlights like what we sell at FlashlightZ typically range from 900 to over 1000 lumens. We sell on model of the Klarus XT2C in particular which shines at 1100 lumens on its maximum setting! In the dark, at close range, this is a literally stunning amount of light.
The strobe function works through the flicker vertigo or "Bucha" effect. The phenomenon is well-documented, especially among helicopter pilots who must be wary of bright light coming through the rotating blades. A bright enough light turning off and on between 4 and 20 Hz can cause many deleterious mental effects, such as disorientation, confusion, headache, and even nausea. The strobe function on tactical flashlights flickers the light within that critical 4 and 20 Hz. Most even change that frequency every few seconds, making it more difficult for the brain to adjust, like the Klarus XT11.
It should be pointed out, of course, that a strobe light has no stopping power. However, the first goal of a civilian when under attack is to escape, not to "win." If you have a tactical flashlight with a strobe function, you can likely gain extremely valuable seconds that will help you to achieve that goal.