The dark truth: how blue light is killing your health

Artificial blue light affects your sleep, mental health, and can trigger the causation of multiple diseases and adverse health conditions.

We're going to unpack what blue light is, why you need to minimize exposure to blue light, and practical tips to reduce your exposure.


For centuries, the sun has been the major source of lighting for humans and other creatures. Our ancestors spent their evenings in darkness and our bodies are biologically wired to follow a circadian rhythm (e.g. a biological clock) that corresponds with the sun.

Fast forward to the 21st century, much of our nights are artificially illuminated and we may be paying a price for the blue light exposure. 

The most obvious result from prolonged exposure to blue light during evening hours is that our sleep suffers. However, this is just the tip of the iceberg. Research shows that blue light may contribute to the causation of cancer, diabetes, heart disease, and obesity.

What is blue light?

As we were taught in high school science classes, there's a wide spectrum of different colors of light. More importantly, not all colors of light affect our bodies the same.

Blue light wavelengths, which are excellent during daylight hours (they boost attention, reaction times, and mood), have a disruptive effect on our bodies at night. The recent proliferation of consumer electronics with LED screens, compact fluorescent/energy efficient lighting, results in an abnormal increase to our exposure to blue wavelengths, especially after sundown. 

Blue light and sleep

All humans have circadian rhythms that are slightly different; however, the average circadian rhythm is 24.25 hours.

Harvard Medical School's Dr. Charles Czeisler showed that daylight keeps a human's body clock aligned with their environment.

Is exposure to blue light at nighttime bad?

Many research studies show a strong link between prolonged exposure to artificial light during evening/nighttime hours (such as working a graveyard shift) to diabetes, obesity and heart disease.

Furthermore, a Harvard study explained the possible connection of blue light to diabetes and obesity.

in this study, the researchers placed 10 people on gradually shifting circadian rhythm schedules. As a result, blood sugar levels increased which threw them into a pre-diabetic state. Simultaneously, levels of leptin, a hormone that leaves people feeling full after a meal, went down.

One major concern over blue light exposure, is that blue light suppresses the secretion of melatonin in the body. As many know, melatonin is a necessary "sleep" hormone that influences circadian rhythms.

Of course intense, bright blue light is especially unideal; however, dim light can interfere with one's melatonin secretion and thus their circadian rhythm.

Stephen Lockley, a Harvard sleep researcher, states that just eight lux (a level of brightness exceeded by most table lamps) has a notable effect on the body. He believes that nighttime exposure to blue light plays a significant reason why so many struggle to get enough sleep. 

While the lack of sleep can sound relatively harmless, ample research has linked short sleep periods to a heightened risk for depression, diabetes and cardiovascular problems.

How does blue light affect your health?

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. Those curlicue compact fluorescent lightbulbs and LED lights are much more energy-efficient than the old-fashioned incandescent lightbulbs we grew up with. But they also tend to produce more blue light.

The physics of fluorescent lights can't be changed, but coatings inside the bulbs can be so they produce a warmer, less blue light. LED lights are more efficient than fluorescent lights, but they also produce a fair amount of light in the blue spectrum. Richard Hansler, a light researcher at John Carroll University in Cleveland, notes that ordinary incandescent lights also produce some blue light, although less than most fluorescent lightbulbs.


LED blue light exposure

There's a significant paradox with blue light: our quest for energy-efficient lighting and desire to reduce our carbon footprint could be at odds with our personal health and wellbeing.

The pig-tail compact flourescent bulbs and LED light have endless benefits in comparison to the old-fashioned incandescent counterpart bulbs; however, they produce a significantly higher amount of blue light. 

Unfortunately, the physical properties of fluorescent lights can not be changed, but there is hope.

Light bulb manufacturers can apply coatings inside the bulbs can be so they produce a warmer, less blue light.


How to protect yourself from blue light at night

  • Use dim red/orange lights for nighttime lighting. This is recommended because red light will not shift your circadian rhythm and suppress melatonin.
  • Put your phone & devices up. Avoid looking at bright screens beginning two to three hours before bed.
  • If you work a night shift or use digital screens at night, we recommend wearing blue-blocking glasses or installing an app (like f.lux) which filters the blue/green wavelength at night, and switches it to warmer, circadian-friendly colors.
  • Increase your exposure to bright light during the day, which will boost your likeliness to sleep at night,. This will also positively affect your mood and alertness the following day.

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