What is Light Trespass?

Mary McMahon
Mary McMahon

Light trespass is a form of light pollution which impinges on other people's personal space. The most familiar example of it is a floodlight which illuminates a neighbor's yard. Many people find this pollution extremely frustrating and annoying, and it can be a source of conflict in a community. For this reason, people are encouraged to think before installing outdoor lighting; approaching a neighbor at the start can also help to encourage a good relationship which will be helpful when resolving future issues.

Light trespass often worsens light pollution, which obscures the night sky.
Light trespass often worsens light pollution, which obscures the night sky.

Essentially, light trespass is unwanted spill light. In addition to being irritating, it is also wasteful, and it contributes to the problem of light pollution. Light trespass is commonly caused by individual light fixtures on homes and other structures, but it can also be caused by poorly directed arena lighting, ambient building lighting, and other sources. This unwanted light is particularly noticeable in urban areas, where many people complain that their homes are never truly dark.

Light trespass can be prevented by turning lights off when they are not needed.
Light trespass can be prevented by turning lights off when they are not needed.

There are a number of ways in which light trespass can be prevented. The most obvious, of course, is turning lights off when they are not needed. It is also a very good idea to take the time to aim lights when installing them, and to think about where spilled light will end up. By aiming lights at the ground, people can also ensure that the lights will serve their intended purpose, which is providing illumination for safety. Many organizations also recommend the use of hoods and shields on lighting to ensure that the light is properly directed.

Many people are not aware that they are committing light trespass, and their neighbors may seethe in silence for some time before mentioning it. When a new light fixture is installed, it pays to turn it on in the evening and take a walk around the neighborhood to see if the light is visible. If you suspect that a light is spilling onto a neighbor's property or into their home, ask them to help you as you reposition the light.

If you are frustrated by an act of light trespass committed by a neighbor, it is a good idea to approach them about it as quickly as possible, and to remember that he or she may not be aware that the light is causing a problem. Try to approach the situation politely, and offer to help your neighbor aim the light more efficiently, or ask if a motion detector could be used to ensure that the light only comes on when it is needed.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


My neighbor across the street likes to light up my house with her newly installed halogen lights any time she is feeling sad, mean, or any other degree of human emotions that she does not understand that come from her own emotional distress.

To complain just feeds it back to her and encourages more unwanted behaviors from her, like yelling at a barking dog.

She will pass soon from diabetes and then I will shoot out the lights before a new neighbor can carry on the tradition of pain sharing.


If you live in an unincorporated area of Riverside County California, a relatively new ordinance (#915) makes light trespass illegal. You must either shield the light(s) downward or shut it off. Violators are given a warning but then fined and even put in jail if they don't comply.

The question you need to ask is, "does lighting up my bedroom make your home more secure?" Does watering my yard make yours greener? Inconsiderate people should be dealt with using the full force of the law.


My neighbors insist on having their porch light on all night in front of my window. I put superglue in their light. It lasted twi weeks, then they got another light. Whenever I talked to them it is obvious that they could not care less if I end up sleep deprived. This has been going on for months. I finally found out that my city has an ordinance about it. The city has told them to take the light down. Yay!


I have the same issue as a007mcguyer in the front, plus their porch light and second door are installed five feet from our bedroom windows. Again, this is in California.


Living near a hospital and university has proven unwise. After three years of my house purchase, both started to grow. Houses and apartments were torn down to make way for new soccer and baseball fields. We're told they can do what ever they want. Lights are sometimes on all night. When we complained, we were asked don't you have curtains?

The hospital has been better, they installed lights that shine directly down, but the signage and new street light illuminate our house so that no lights need come on for trips to the potty. But the telescopes have not been out in years.

I would move if I could find another 100-plus year old house. The neighbors have added to this light trespass. Arrrgh!


I love the mirror idea. Some people just won't listen to when you politely mention something they are in the wrong about. I think the mirrors will give them the hint without anyone having to say a word.


I'm really considering just printing out this article and anonymously mailing it to my neighbor. We live on a small, townhouse-lined cul-de-sac and the floodlights he has installed over his garage are on and off all night long (and, all day long -- it gets dark up here during the winter in Anchorage). Worse, they shine right in our bedroom window. He has the sensitivity and timer set at the max and has two unshielded over-100W bulbs. Anything will trigger it -- an animal, a car driving by, the wind in the trees. Much too often, I am googling "I hate my neighbors' floodlights" and variations thereof in the middle of the night as they illuminate our bedroom and destroy the otherwise beautiful Alaskan night sky. We have spent hundreds on high-quality blackout blinds and if we can't manage to convince the neighbor to adjust his lights in some fashion, we will have to spend even more to seal some small seams around the edges of our blinds where, aggravatingly, his light creeps through.

I'm all for politely confronting people, but you have to pick and choose your battles, and no matter how nicely you word it, some people just see confrontation as confrontation. Since we are younger than this neighbor and bought our house about six months ago, methinks asking him to reposition his floodlights that have clearly been that way for years will be met with, at best, indifference. I should mention that of the 12 townhomes on our cul-de-sac, he is the only one with floodlights. We're not the only home they shine on, either. All of my other neighbors are silently seething like this article states, or nobody cares. I'm betting it's the latter. His lights are absurd and it floors me that other people let him carry on with the rudeness, totally unchecked. I don't know how his lights got past me when we were under contract on the home. I guess I was pretty enamored with our house.

In conclusion: I really hate other people's behavior sometimes. Also, everyone has a personal responsibility to not be a jerk.


a well positioned strobe light will do the trick. after five years of being blinded by my neighbor's seven spotlights 20 feet from my house, hitting most of inside of my house and blinding us trying to get to front door. I tried talking, flashing lights back using mirrors and putting the car on the lawn with brights on, but they couldn't stand the strobe for more than a week!


a007mcguyver -- maybe you can install some mirrors where the flood lights are strategically placed to redirect the light back into the floodlight owners' property.


These are all very helpful comments, but what do you suggest when one neighbor intentionally installs floodlights and intentionally directs them at neighbors windows out of spite? I live in California and my jurisdiction doesn't have a local ordinance that addresses light trespass from one residential property to another, only from a commercial property onto a residential property.

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