Police officers and security companies agree that a porch light may discourage criminals from breaking into your house at night. Porch lights can assist you to avoid falls and fumbling with keys when you arrive at your door. Lights allow your neighbours to see if a stranger is at your door.
Motion Sensor Lights Provide More Security
Many of the same sources agree that always leaving the porch light on at night, or just leaving it on when you leave, will alert criminals that you are gone. Leaving a light burning all night long wastes energy. Another concern is that some people find it difficult to sleep if there is a light coming through the window at night.
If you want to use a porch light to deter criminal activity, use lights with a motion sensor. This solution wastes less energy because the light is only on when something is moving. If there are lights on in the house, even if they are on a timer, it suggests someone may be home. Criminals are more likely to bypass the house with motion sensor lights than a house where the lights are on only when you are gone or a house where the porch light is always on.