The chances of deer being on the road at the time when modulators are most useful, i.e., bright daylight, would be might slim I think. If the modulator is on when you are riding at dusk, then you could encounter deer as that is when deer are most active. But I have a hard time believing that a modulated light would cause a deer to freeze and quicker than a steady light. There is a reason for the phrase, "deer in the headlights." If one is riding at dusk where deer are common, and you think it may be a problem, turn the modulator off.