Could Light Pollution Be Harming Your Health?

Blue Light


Lifestyle habits play a major role in how healthy you are, but also environmental factors, the forces you’re exposed to every day also matter. Some of these are factors that you might not think about. One of these is light pollution. We hear a lot about air and noise pollution, but light pollution can also impact your health. Let’s take a closer look at what it is, how it influences health and well-being, and how you can use it to your advantage.

What is Light Pollution?

Light pollution is the excessive light humans are exposed to as a byproduct of living in a civilized society. Sources of light pollution include interior and exterior lighting from buildings, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues.

Excess light exposure is more of a problem in highly industrialized and densely populated areas of North America, Europe, and Japan and in major cities in the Middle East and North Africa like Riyadh and Dubai.If you live in a busy city, you’re exposed to more light pollution than someone who lives in a rural area, although people also create their own light pollution by lighting up their homes at night or leaving lights on.

In terms of health risk, it’s not just the amount of light humans are exposed to but also the timing of the light exposure. As a human, you function best when your eyes are exposed to natural light early in the day and sleep in complete darkness. The same would not be true of a nocturnal animal.

In fact, appropriately timed light exposure is critical. Light exposure during the day and complete darkness at night help properly set the internal biological clock that you and all humans and animals have.  Likewise, light exposure at night and lack of natural light during the day disturb the internal biological clock and its natural rhythms and may have health consequences.

Circadian rhythms affect all aspects of human health, including hormone levels, digestion, mental function, blood sugar control, and even immune function. Hormones that affect these processes are dictated by the internal biological clock and the rhythms this clock establishes. If your internal clock is disrupted by light exposure at the wrong times, your body may release hormones at inappropriate times and processes like sleep, digestion, immunity, and cellular repair may work as efficiently.

The Problem of Blue Light Exposure at Night

Light comes in different wavelengths. Red light has a long wavelength while blue light has a short wavelength and high frequency, meaning it’s more energetic. Blue light is also more problematic if your eyes absorb it at night. Exposing your eyes to blue light in the evening, when your eyes expect darkness, reduces the amount of melatonin released prior to sleep and during the night.

Melatonin is an antioxidant hormone that helps bring on sleep and improve sleep quality. It’s also important for properly setting your biological clock. For example, some people take a melatonin supplement to help reset their biological clock when they change time zones. (Jet lag) Disrupted release of melatonin has also been linked to breast cancer and prostate cancer in studies.

According to Harvard Health, blue light exposure at night not only interferes with sleep, but also increases the risk of health problems such as heart disease, type 2 diabetes, obesity, and some forms of cancer.

Blue Light Is in Your Home Too

Where does all the blue light come from? One of the most potent sources of blue light are devices, like tablets, smartphones, and computers. So, if you prop yourself up in bed and stare at technology before bedtime, you’re getting a dose of blue light pollution.

Other sources of light pollution include light coming in from the outside through cracks in the shades or curtains from streetlights and lights and outside lights that people keep on at night. People who live in large cities also get light exposure from lit-up signs and traffic. All light at night disrupts circadian rhythm and melatonin release. However, blue light is the most powerful disruptor of the internal biological clock.

Fortunately, you have some control over how much and when you expose your eyes to blue light. Let’s look at some ways to reduce your exposure to blue light at night:

  • Reduce the time you spend looking at digital screens.
  • Turn off all electronic devices one hour before bedtime (including TVs and smartphones).
  • If you must use devices at night, turn on the night shift feature on iOS or Android.
  • Remove all light sources from your bedroom.
  • Use curtains, shades, or blinds on windows to block sunlight and other outdoor light sources from coming into your room at night.
  • Cover windows with blackout curtains, shades or blinds and install blackout paint on windows.
  • Turn off TVs, computers. and other electronics when not in use. If you leave them on standby mode, they still emit some light, even if it’s faint.
  • Move alarm clocks away from your face and use the snooze feature if possible, so that you don’t need to look at it in the middle of the night.
  • Be aware that blue light comes from a variety of devices including televisions, smartphones, tablets, d-readers, gaming consoles, LED lights, fluorescent lights, and sunlight.

Also, getting natural light early in the day helps properly set your biological clock. Preferably, expose your eyes to natural sunlight before noon and earlier is better. So, throw open the curtains or blinds as soon as you wake up. Don’t eat your breakfast in the dark. But also, limit exposure to light sources at night and ensure your bedroom is free of blue light sources.

The Bottom Line

Light pollution is a threat to human health because it can disrupt hormones and sleep and potentially increases the risk of health problems such as obesity, type 2 diabetes, and heart disease. Light pollution is a problem but there’s a lot you can do to reduce your exposure to it at night. Hopefully, these tips will help you get a better night’s sleep and reduce your exposure to light pollution.


  • Cao M, Xu T, Yin D. Understanding light pollution: Recent advances on its health threats and regulations. Journal of Environmental Sciences. 2023;127:589-602. doi:10.1016/j.jes.2022.06.020.
  • “Biological Clocks – an overview | ScienceDirect Topics.” https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/biological-clocks.
  • “The Color of the Light Affects the Circadian Rhythms | NIOSH | CDC.” 01 Apr. 2020, https://www.cdc.gov/niosh/emres/longhourstraining/color.html.
  • “Blue light has a dark side – Harvard Health.” 07 Jul. 2020, https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side.
  • “Light pollution: Environmental impact, health risks and facts.” 05 Apr. 2022, https://www.livescience.com/light-pollution.
  • Spivey A. Light at night and breast cancer risk worldwide. Environ Health Perspect. 2010 Dec;118(12):a525. doi: 10.1289/ehp.118-a525. PMID: 21123149; PMCID: PMC3002207.

Related Articles By Cathe:

7 Little-Known Tips for Getting a Better Night’s Sleep

5 Ways Lack of Sleep Affects Brain Health and Mood

4 Ways Lack of Sleep Increases the Risk of Weight Gain

4 Ways Lack of Sleep Makes It Hard to Lose Belly Fat

Why Lack of Sleep is Bad for Your Heart

Does Lack Of Sleep Increase the Risk of Training Injuries?

How Does Lack of Sleep Affect Your Metabolism?

Sleep and Health: It’s Not Just the Amount of Sleep but the Amount of Deep Sleep

What is the Ideal Amount of Sleep for Good Health?

How Lack of Quality Sleep Limits Muscle Growth

Hi, I'm Cathe

I want to help you get in the best shape of your life and stay healthy with my workout videos, DVDs and Free Weekly Newsletter. Here are several ways you can watch and work out to my exercise videos and purchase my fitness products:

Get Your Free Weekly Cathe Friedrich Newsletter

Get free weekly tips on Fitness, Health, Weight Loss and Nutrition delivered directly to your email inbox. Plus get Special Cathe Product Offers and learn about What’s New at Cathe Dot Com.

Enter your email address below to start receiving my free weekly updates. Don’t worry…I guarantee 100% privacy. Your information will not be shared and you can easily unsubscribe whenever you like. Our Privacy Policy