Too much light can be a problem. 

Too much light can be a problem. 
Sometimes, lights shine where they should not. A bright light might shine into a window. This can make it hard to sleep. 
Other lights shine up into the sky. This creates a bright haze. This haze can hide the stars. It makes the night sky look bright instead of dark.
Extra light can also hurt plants and animals. It can even be hard for people to see well. This can make driving on roads tricky.
We can fix this. We can use better bulbs. We can also change how we use lights. 
Light pollution is the change in natural light patterns. 
There are a few main kinds of light pollution. One kind is light trespass. This is when unwanted light shines into a place, like a bedroom window. This can make it hard to sleep. Another kind is skyglow. This is a bright haze in the sky above cities. It is made by light reflecting and bouncing around in the air. 
Other problems include glare and light clutter. Glare is a bright light that can make it hard to see. This can be dangerous for drivers. Light clutter is when too many lights are grouped together. This can be distracting or confusing. 
We can help fix these problems. We can use better light fixtures. We can also use better bulbs. These changes help protect the dark night sky.
Light pollution is a change in the natural patterns of light and dark. 

There are several ways light pollution works. One way is called light trespass, which is when unwanted light enters a place. For example, a strong light might shine through a bedroom window. This can make it very hard for people to sleep. Another way is skyglow, which is a bright haze above cities. 
Light pollution also includes over-illumination and light clutter. Over-illumination is using much more light than is actually needed. This can waste a huge amount of electricity. In the United States, homes used 81 billion kilowatt hours of electricity for lighting in 2020. 

People began to notice the harm of light pollution in the late 1800s. However, real efforts to fix it did not start until the 1950s. In the 1980s, a global movement for dark skies began. This led to the founding of the International Dark-Sky Association (IDA). 
Today, light pollution is a very large issue for our planet. It is estimated that 83% of the world's people live under light-polluted skies. In North America, 80% of people cannot see the Milky Way galaxy. Globally, light pollution increased by at least 49% between 1992 and 2017. We can help solve this by using better light bulbs or fixtures. Changing how we use light can help protect both our health and the stars.
Light pollution is the alteration of natural light and dark patterns in ecosystems. This phenomenon results from the use of artificial lighting in poor or excessive ways. While it can occur during the day, its effects are most visible at night. This is because of the high contrast between artificial light and the dark sky. Light pollution is a major side effect of our industrial civilization. It affects human health, disrupts entire ecosystems, and spoils beautiful natural environments. 
There are several distinct categories of light pollution. One type is light trespass, which occurs when unwanted light enters a specific property. For example, a strong outdoor light might shine through a bedroom window. This can cause sleep deprivation for the people inside. Another type is skyglow, which is a bright haze seen above cities. This haze is created when artificial light reflects and bounces around in the atmosphere. 
Glare is a specific type of light that can be very disruptive. It is often classified into three different levels of intensity. Blinding glare is so bright that it can cause temporary or permanent vision deficiencies. Disability glare, such as the light from oncoming cars, reduces a person's ability to see clearly. This can happen when light scatters in the eye or reflects off dark areas. Discomfort glare is less dangerous but can be very annoying or cause fatigue. In some cases, bad lighting is considered a public health hazard. 
Over-illumination refers to the excessive and unnecessary use of artificial light. This often happens because of improper design or incorrect choices in light bulbs. Many people also hold the misconception that more light always equals more safety. This is not a proven fact and can actually make problems worse. Over-illumination also leads to massive amounts of wasted electricity. In the United States, homes used 81 billion kilowatt hours of electricity for lighting in 2020. Commercial and manufacturing buildings used even more in 2018. 
Light clutter is another way that artificial light causes problems. This occurs when there are excessive groupings of lights in one area. You might see this with brightly lit advertisements or poorly designed streetlights. Light clutter can be very distracting to people, especially drivers. These groupings of lights can generate confusion and even lead to accidents. 
Human awareness of these harmful effects began in the second half of the 19th century. However, organized efforts to fix the problem did not truly start until the 1950s. In the 1980s, a global dark-sky movement emerged to protect the night. This led to the founding of the International Dark-Sky Association (IDA). Today, many educational and advocacy organizations exist in countries all over the world. They work to teach the public and push for new legislative changes. 
The scale of light pollution is quite large and continues to grow. It is estimated that 83% of the world's people live under light-polluted skies. In North America, 80% of people cannot see the Milky Way galaxy. Globally, light pollution increased by at least 49% between 1992 and 2017. About 23% of the world's land area is affected by skyglow. We can help reduce these impacts by adjusting light fixtures or using better bulbs. Solutions like indirect lighting can also help manage how light is used.
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