How Light Pollution is Ruining Your Health

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Dr. Mercola
November 20 2008

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How Light Pollution is Ruining Your Health

Humans are diurnal creatures, with eyes adapted to living in the sun's light. Because of this, we’ve engineered the night for our own comfort by filling it with light.

Light pollution is largely the result of poor lighting design, which allows artificial light to shine outward and upward into the sky. Wherever human light spills into the natural world, some aspect of life -- migration, reproduction, feeding -- is affected.

Scientists speak of songbirds and seabirds being "captured" by searchlights, circling and circling in the thousands until they drop. Migrating birds are apt to collide with brightly lit tall buildings. Many nocturnal mammals forage more cautiously under the permanent day of light pollution, because they've become easier targets for predators.

Like most other creatures, humans need darkness. The regular oscillation of waking and sleep is a biological expression of the regular oscillation of light on Earth. At least one new study has suggested a correlation between higher rates of breast cancer in women and the nighttime brightness of their neighborhoods.

Sources:

National Geographic November 2008

Dr. Mercola's Comments:

This was a fascinating article in National Geographic. I subscribe to this magazine for the amazing nature photography, but this was an excellent article on a health topic.

Light pollution refers to “any adverse effect of artificial light, including sky glow, glare, light trespass, light clutter, decreased visibility at night, and energy waste,” writes the International Dark-Sky Association (IDA).

Obvious examples would be the glow that can be seen from miles outside of a big city, or the absence of stars in the night sky if you live in an urban environment. More subtle examples of light pollution are the strips of light that come in around your curtains at night, or even the glow from your clock radio. All of these have the potential to negatively impact your health and the natural rhythms of nature. IDA writes:

“Light pollution wastes energy, affects astronomers and scientists, disrupts global wildlife and ecological balance, and has been linked to negative consequences in human health.”

One such consequence is cancer.

How Light Pollution May Cause Cancer

While it’s typically thought that your biological clock is what tells you when it’s time to wake up or go to sleep, light and dark signals actually control your biological clock. To get more specific, a part of your brain called the Suprachiasmatic Nucleus (SCN) -- a group of cells in your hypothalamus -- controls your biological clock. And the cells that make up your SCN respond to light and dark signals.

Light actually travels through your eye’s optic nerve to your SCN, where it signals your body’s clock that it’s time to wake up. Light also signals your SCN to initiate other processes associated with being awake, such as raising your body temperature and producing hormones like cortisol.

Meanwhile, when your eyes signal to your SCN that it’s dark outside, your body will begin to produce melatonin The level of melatonin produced is related to the amount of exposure you have had to bright sunshine the previous day. The less bright light exposure the lower your melatonin levels.

Melatonin is known as a hormone that helps you sleep and radically decreases your risk of cancer. There are many studies on this powerful association. The more your sleep is disrupted by light pollution, the lower your melatonin levels and the greater your risk of developing cancer becomes.

Melatonin is secreted primarily in your brain and at night it triggers a host of biochemical activities, including a nocturnal reduction in your body's estrogen levels. It’s thought that chronically decreasing your melatonin production at night -- as occurs when you’re exposed to nighttime light -- increases your risk of developing cancer.

In fact, one of the first studies linking cancer to light showed that blind women have a 36 percent lower risk of breast cancer compared to sighted women. Why? Because they are unreceptive to light. This means that their bodies maintain high melatonin levels at night regardless of how much light is in the room.

Artificial Light’s Impact on the Environment

Organisms evolved to adjust themselves to predictable patterns of light and darkness. Once artificial light effectively varied the length of a day, something that happened less than a century ago, the average night's sleep decreased from around nine consistent hours to roughly seven, varying from one night to the next.

The irregularity prevents circadian rhythms from adjusting to a pattern, and creates a state of permanent "jet lag." This is true not only in humans but in many other species as well. IDA lists many of the far-reaching effects that light pollution has on the environment:

• Lighted towers and tall buildings confuse migrating and local birds, causing them to collide or circle the lights until they die of exhaustion.
• Sea turtle hatchlings are meant to crawl toward the ocean, guided by the light of the moon. Coastline lighting confuses them, drawing them away from the ocean instead of toward it.
• Glowworms and fireflies communicate through light, and artificial lighting makes this difficult.
• Intense lights for fishing at night attract large numbers of fish, leading to over-fishing and contributing to the decline of fish worldwide.
• Nighttime lighting from sports stadiums can stop the mating activity of nearby frogs.

So while electricity and efficient lighting have clearly provided major benefits to society, these benefits come with a price. A sensible solution, as IDA suggests, is to use outdoor light at night only when and where it is needed and at appropriate lighting levels. They also suggest using fully shielded, light-efficient fixtures aimed directly at the ground, and incorporating timers and sensors to shut off lights when they’re not needed.

Conducting a Light Check in Your Bedroom

Sleeping in a pitch-black bedroom is an important and relatively easy lifestyle choice to make for your health. Even the dim glow from your clock radio could be interfering with your ability to sleep, and more importantly, your long term health and risk of developing cancer.

Personally, I sleep in a room that is so dark, that I can’t see my hand in front of my face. If your bedroom is currently affected by light pollution, you will notice a major improvement when you eliminate it.

To get your room as dark as possible:

• Install blackout drapes
• Close your bedroom door if light comes through it, and even put a towel along the base to prevent light from seeping in
• Get rid of your electric clock radio (or at least cover it up at night)
• Avoid night lights of any kind
• Keep all light off at night (even if you get up to go to the bathroom) -- this includes the TV!

If you are interested in finding more information on this vital subject, I highly suggest reading Lights Out: Sleep, Sugar, and Survival by T. S. Wiley and Bent Formby. The authors believe that it is light, not what we eat or whether we exercise, that causes obesity -- and diabetes, heart disease and cancer. I recently had the pleasure of meeting Dr. Wiley at a conference I attended.

Now, if it’s been awhile since you’ve had the luxury of gazing up at a truly dark night sky, you might want to plan your next vacation around it. IDA has an inspiring list of vacation spots in the United States and world where you can take stargazing to a whole new level.

Related Links:

Sleeping Patterns Are Governed by Light

With More Night Light Comes A Greater Risk of Leukemia

Light During Sleep Affects 'Body Clock'

Community Comments (24)

Posted On Nov 04, 2008

I can't argue about how this issue effects animals.

But i strongly disagree with the idea that humans need total darkness in order for deep sleep. Few nights are truly dark between the stars & moon. And most of our ancestors slept by firelight in order to stay warm. Unless they stayed in a cave without firelight, deep darkness is rare.

I woke up in the night a couple of days ago & discovered that the power was off. So i was looking out into my neighborhood in a small, rural area without a single man made light as far as i could see. It was NOT dark. There was cloud cover because it had been raining, but even with the clouds the moon was providing considerable light.

I keep our bedroom dark with no artificial light, but we do not sleep in total darkness. I don't believe that is possible without a lot of work to create it, & not something that was "natural" to mankind even before electricity.

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Katee Roux

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JAKMVX

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Posted On Nov 05, 2008

I don't believe that primitive man slept openly under the light of the stars and moon. This would expose them to the elements, pests and predators. More likely, they were huddled under hides, inside caves or makeshift shelters, or teepees, etc.

Light destroys my sleep, even just a little tinge of it seeping through the gap at the top or bottom of the curtains. I've seen research studies where people sleeping in completely dark environments were exposed to tiny beams of light somewhere on their exposed skin. Brain waves indicated a reaction to that small point of light.

Perhaps some individuals feel they sleep fine in lighter environments, but for me, I'll take a cave any night!

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rajsanand

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Posted On Nov 20, 2008

There you go again believing the anthropologists.

I think you take the cavemen movies seriously.

As far as civilization can go, all evidence that shows that there were much advanced and civilized communities existing before us has been deliberately ignored.

All these cavemen theories are all theories from the "behind" just like your theory of light. :-P.

If you read the vedas, humans have been living in civilised society for more that 25000 years, but then "those are myths" arent they ??

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Katee Roux

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Posted On Nov 21, 2008

When i spoke of "our ancestors" i was not speaking of some long-distant cave people. For the past 4000 or so years of history many civilizations lived in houses or fixed dwellings. If they lived in cold weather climates, they slept close to the fire for heat. If they were a nomadic people, they slept under the stars & moon. There are people who believe sleeping in moonlight is healthy

If you like sleeping in total darkness, fine. But put it down as a personal preference. I am not debating that artificial light, something electrically generated, is not good to sleep by. I don't consider firelight or moonlight or starlight artificial.

I believe that sleeping in total darkness is artificial. Short of sleeping in a cave, it doesn't happen naturally. And to depend upon total darkness is to be very inflexible. I see it as limiting as a mother who chooses to rock her child to sleep for each bedtime & nap. The child becomes dependent upon that comforting, & has difficulty adjusting to other situations.

I agree with Lori who feels noise pollution is much more disturbing. I prefer a quiet room to sleep.

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Posted On Nov 20, 2008

I believe that one of our main connections with the universe is through light. Artificial light is empty of universal information. Artificial light may be one of the reasons for our disconnect with the natural forces that animals and groups like the Aboriginees use every day.

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snowfallinchina

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Posted On Nov 20, 2008

I'm kind of with the idea that total darkness is not necessarily what our ancestors went through. My lights are off at night time, no night light, curtains closed, but if I get up to go to the bathroom, I can see my way there! Not being able to see my hand in front of my face seems a bit ludicrous. In fact, whenever I end up taking a 30 minute nap during the day, I like to lay on my couch, right beside the window, with the sun shining in, and close my eyes and fall asleep with the sun shining on me.

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beht

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Posted On Nov 20, 2008

Just because primitive humans did something does not make it a wise thing to emulate. Cavemen did some pretty stupid things, I'll bet, that you would not want to repeat. As for darkening your bedroom, try wearing a blindfold - cheap and totally effective.

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Mr.AK

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Posted On Nov 04, 2008

Another great argument for having really good window treatments! Get accustomed to the deeper sleep you get in a truly dark room and you won't want to sleep if there is even the smallest level of light present.

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Magnolia

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Julieanne

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Posted On Nov 21, 2008

Magnolia, I live in Western Australia, where the summers can be very hot. I need to leave the windows and curtains open to allow any cool breeze to cool the house (and me) down. This allows the morning light to wake me up - though sometimes not!

I would feel suffocated in summer if I had all the windows covered. Luckily, there is not a lot of artificial light coming through, as I sleep at the back of the house, away from the streetlight.

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