Security lights do deter burglars but more so if there are other buildings and people about, as obviously they do not wish to be seen. However, they are known to still just knock on the door and if there is no answer wait for the light to go out and then continue to break-in.
Prevention is better than cure and if you are at home you will be alerted that someone is on your property, also security lights camera views if you have CCTV on your home and this is a true deterrent to the would-be invader.