Don't Be Afraid of the Dark: The Surprising Link Between Light Pollution and Cancer

Do we need nighttime darkness to stay healthy? After finding a correlation between light pollution and increased risk of cancer, researchers say yes.

There are plenty of arguments against lighting the night sky: It wastes energy, blots out stars and messes with the nocturnal habits of animals in a big way. Now there’s another reason, one that could go a long way toward convincing humans that whatever sense of safety is conferred by nighttime lighting, it isn’t worth the risk. It turns out that light pollution may be a cancer risk.

That statement is bold, but increasingly the science is proving it out. Humans, as well as many animals and plants, need regular exposure to darkness to maintain what’s called the circadian rhythm—essentially the body’s internal clock, which governs various bodily functions. Of particular interest to researchers is the fact that darkness at night tells the body to produce certain hormones, most importantly melatonin, which not only aids sleep, but also helps to maintain immune system function.

In several studies conducted over the past decade, scientists have found that increased exposure to light at night correlates to higher cancer rates, particularly for those cancers like breast or prostate that require hormones to grow. Women who work the night shift have been shown to have higher risks of breast cancer, while blind women have lower-than-average risk. In 2009, a landmark study by epidemiologist Dr. Richard Stevens, of the University of Connecticut, compared cancer rates and the presence of light at night across 164 countries and found that women in industrialized, highly lit countries had a 30 to 50 percent higher risk of breast cancer than those in countries with less light pollution.

That last study would be contentious had Stevens not been researching breast cancer for decades, and had he not already studied most of the other elements that might explain such a difference between developed and less developed countries. “Back in the 80s, we were all convinced that it had to be the high-fat Western diet that was causing the spike in breast cancer rates, but then the really good dietary models started to come in and nothing proved it out,” Stevens says. “Then we thought, ‘okay, maybe it has to do with the average age of the first child,’ because that typically gets older as societies get richer, but that wasn’t it either. We looked at a couple of other things that typically change when a society becomes more developed as well, but we’ve looked carefully at all of them, and those changes cannot account for the vast majority of the increase. So what else could it be? That’s how I got into this light at night deal.”

Stevens authored some of the first studies linking light at night (called LAN by scientists) to cancer in the late 1990s and early 2000s and since then the evidence has continued to mount. Light pollution has now been linked to a host of mood disorders as well, and even to obesity and diabetes. The International Agency for Research on Cancer (IARC, part of the World Health Organization) officially deemed shift work a “carcinogen” in 2009. There is, of course, more research to be done, but given the evidence out there already Stevens calls light pollution “the worst thing we’ve done to ourselves and the planet since global warming.”

The good news is that light pollution is a relatively new problem and it’s entirely reversible, starting with ensuring nighttime darkness at home wherever possible. According to Joan Roberts, Ph.D., a Fordham University professor whose work on the importance of natural light in maintaining circadian rhythms also touches on the need for darkness, “It’s not that you need total darkness, but you need to have NO stray light that is in the blue or green region (400-600 nm) in the late evening.”

The blue/green light is what is emitted from TVs , computers, clock radios and other gadgets (cell phones, Blackberry's, etc) or from what Roberts calls “light trespass,” which comes in from the outside, through your windows. “Light from the blue region stimulates a ‘wake up’ circadian response in the body and blocks the production of melatonin in the brain.”

The same thing happens if you get up in the middle of the night to go to the bathroom and turn the light on. Stevens recommends using a red night light instead, because red light does not suppress melatonin production. Unfortunately, popping a few melatonin tablets won’t solve the problem, and in fact it could actually exacerbate it. Researchers have found that creating an artificial spike in melatonin makes the circadian disruption worse.

“Another thing: If you wake up in the night, stay in the dark,” Stevens says. “It’s completely normal to awaken during the night. They used to say if it happened, you should get out of bed and go watch TV or read a book. That is completely wrong. We’ve completely lost sight of so many things in modern life – that period of quiet wakefulness in the dark … we evolved with that.”

Photo of L.A. at night by Aaron Logan, courtesy Wikimedia Commons.


The healthcare systems in the United States and the United Kingdom couldn't be more different.

The UK's National Health Service is the largest government-run healthcare system in the world and the US's is largest private sector system.

Almost all essential health services in the UK are free, whereas in America cost can vary wildly based on insurance, co pays and what the hospitals and physicians choose to charge.

A medical bill in the US

One of the largest differences is cost. The average person in the UK spends £2,989 ($3915) per year on healthcare (most of which is collected through taxes), whereas the average American spends around $10,739 a year.

So Americans should obviously be getting better care, right? Well, the average life expectancy in the UK is higher and infant mortality rate is lower than that in the US.

RELATED: The World Health Organization declares war on the out of control price of insulin

Plus, in the U.S., only 84% of people are covered by private insurance, Medicare or Medicaid. Sixteen percent of the population are forced to pay out of pocket.

In the UK, everyone is covered unless they are visiting the country or an undocumented resident.

Prescription drugs can cost Americans an arm and a leg, but in the UK, prescriptions or either free or capped at £8.60 ($11.27).

via Wikimedia Commons

The one drawback to the NHS system is responsiveness. In the UK people tend to wait longer for inessential surgeries, doctor's appointments, and in emergency rooms. Whereas, the US is ranked as the most responsive country in the world.

RELATED: Alarmingly high insulin prices are forcing Americans to flock to Canada to buy the drug

The New York Times printed a fair evaluation of the UK's system:

The service is known for its simplicity: It is free at the point of use to anyone who needs it. Paperwork is minimal, and most patients never see a bill. … No one needs to delay medical treatment until he or she can afford it, and virtually everyone is covered. …

According to data from the Organization for Economic Cooperation and Development, the United States spent 17.2 percent of its economic output on health care in 2016, compared with 9.7 percent in Britain. Yet Britain has a higher life expectancy at birth and lower infant mortality.

Citizens in each country have an interesting perspective on each other's healthcare systems. UK citizens think it's inhumane for Americans have to pay through the nose when they're sick or injured. While Americans are skeptical of socialist medicine.

A reporter from Politics Joe hit the streets of London and asked everyday people what they think Americans pay for healthcare and they were completely shocked.


Bans on plastic bags and straws can only go so far. Using disposable products, like grabbing a plastic fork when you're on the go, can be incredibly convenient. But these items also contribute to our growing plastic problem.

Fortunately, you can cut down on the amount of waste you produce by cutting down on disposable products. And even more fortunately, there are sustainable (and cute) replacements that won't damage the environment.

Coconut bowls


Who says sustainable can't also be stylish? These cute coconut bowls were handmade using reclaimed coconuts, making each piece one of a kind. Not only are they organic and biodegradable, but they're also durable, in case your dinner parties tend to get out of hand. The matching ebony wood spoons were polished with the same coconut oil as the bowls.

Cocostation Set of 2 Vietnamese Coconut Bowls and Spoons, $14.99; at Amazon

Solar powered phone charger


Why spend time looking around for an outlet when you can just harness the power of the sun? This solar powered phone charger will make sure your phone never dies as long as you can bask in the sun's rays. As an added bonus, this charger was made using eco-friendly silicone rubber. It's win-win all around.

Dizaul Solar Charger, 5000mAh Portable Solar Power Bank, $19.95; at Amazon, $19.95; at Amazon

Herb garden kit

Planter Pro

Put some green in your life with this herb planter. The kit comes with everything you need to get a garden growing, including a moisture meter that helps you determine if your herbs are getting the right amount of food to flourish. All the seeds included are certified to be non-GMO and non-hybrids, meaning you can have fresh, organic herbs right at your fingertips.

Planter Pro's Herb Garden Cedar Planter, $39.00; at Amazonedar Planter, $39.00; at Amazon

Reusable Keurig cups

K & J

Keurig cups are convenient, but they also create a ton of plastic waste. These Keurig-compatible plastic cups are an easy way to cut down on the amount of trash you create without cutting down on your caffeine. Additionally, you won't have to keep on buying K Cups, which means you'll be saving money and the environment.

K&J Reusable Filter Cups, $8.95 for a set of 4,; at Amazon

Low-flow shower head


Low-flow water fixtures can cut down your water consumption, which saves you money while also saving one of the Earth's resources. This shower head was designed with a lighter flow in mind, which means you'll be able to cut down on water usage without feeling like you're cutting down on your shower.

Speakman Low Flow Shower Head, $14.58; at Amazon

Bamboo safety razor


Instead of throwing away a disposable razor every time you shave, invest in an eco-friendly, reusable one. This unisex shaver isn't just sustainable, it's also sharp-looking, which means it would make a great gift for the holidays.

Zomchi Safety Razor, $16.99; at Amazon

The Planet
Instagram / Leonardo DiCaprio

This August, the world watched as the Amazon burned. There were 30,901 individual fires that lapped at the largest rainforest in the world. While fires can occur in the dry season due to natural factors, like lightning strikes, it is believed that the widespread fires were started by loggers and farmers to clear land. Brazil's president, Jair Bolsonaro, cites a different cause: the actor Leonardo DiCaprio.

DiCaprio wasn't accused of hanging out in the rainforest with a box of matches, however President Bolsonaro did accuse the actor of funding nonprofit organizations that allegedly set fires to raise donations.

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