Human Health

Exposure to Light Pollution Harms Your Health

Research suggests that light pollution negatively effects human health, increasing risks for obesity, depression, sleep disorders, diabetes, breast cancer and more.

Many species (including humans) need darkness to survive and thrive.

— American Medical Association Council on Science and Public Health (2012)

Circadian Rhythm and Melatonin

Like most life on Earth, humans have a biological clock called your circadian rhythm. It is a sleep-wake pattern governed by the day-night cycle. Artificial light at night disrupts that cycle.

Our bodies produce the hormone melatonin in response to our circadian rhythm. Melatonin helps keep us healthy. It induces sleep, boosts the immune system, lowers cholesterol, and helps the functioning of the thyroid, pancreas, ovaries, testes and adrenal glands. Nighttime exposure to light pollution suppresses melatonin production.

Blue Light is the Most Harmful Type of Light Pollution

Exposure to blue light at night is harmful. Unfortunately, most LEDs used for outdoor lighting — as well as computer screens, TVs, and other electronic displays — have a white colour which is dominated by blues.

According to experts at Harvard Medical School,

“If blue light does have adverse health effects, then environmental concerns, and the quest for energy-efficient lighting, could be at odds with personal health. ”

A 2016 American Medical Association report expressed concern about exposure to blue light from outdoor lighting and recommends shielding all light fixtures and only using lighting with 3000K colour temperature and below.

To minimize harm from blue light in your home, choose the right light bulb and download a colour temperature app that adapts your electronic screen to the time of day – cool light during the day and warm light at night.

Colour Temperature Apps:

  • F.lux is available for Mac OS/X, Windows, Linx and (jailbroken) iPhones and iPads.
  • For those with Apple devices using the iOS 9.3 operating system and above, the Night Shift app is pre-installed. Click here to learn how to use it. 
  • Lux is available for Android devices free or for pay.
  • Twilight is available for smartphones or tablets.

Choosing the Right Bulb


In this picture both lights are “white” but the bulb on the left is rich in blue light, while the one on the right isn’t. The warmer light on the right is the better, healthier one to choose.

All packaging for new light bulbs provides colour temperature information. Use low-colour temperature light sources for interior and exterior light. Their light is less harsh and less harmful to human health and the environment. Look for warm white sources with a colour temperature of 3000K or lower.

Kelvin Temperature Scale

Higher colour temperatures mean white light that is more blue-ish and less warm, the kind that should be avoided after dusk.

3 types of light bulbs showing different effects of colour temperatures.
Image: Wikipedia, shows three different white lights with blue, yellow and orange tints to them. The orange 2700K light is the healthiest and most environmentally positive type to chose.

Glare from Bad Lighting is a Safety Hazard

Glare from poorly shielded outdoor lighting is also harmful to your health because it decreases vision by reducing contrast. This limits our ability to see potential dangers at night. Ageing eyes are especially affected.

“Glare from nighttime lighting can create hazards ranging from discomfort to frank disability.”

American Medical Association Council on Science and Public Health (2012)