What is Junk Light and Why is it Bad for You?

traditional light bulb standing on end

Article at a Glance: 

  • Junk light is a common occurrence found in artificial light sources like LEDs and fluorescents. 
  • Junk light specifically refers to blue, green and violet light. 
  • We didn’t always have junk light, our ancestors used to solely rely on natural sunlight and fire. 
  • Technological advances in lighting led to incandescent, halogen, fluorescent and LED bulbs. Greater access to lighting has resulted in an “always-on” culture and overexposure to certain wavelengths. 
  • Too much artificial blue light during the daytime can zap your energy and negatively affect how you feel and function. 
  • Too much artificial blue, green and violet light at night can suppress your body’s ability to produce the melatonin you need to fall and stay asleep. 
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Junk light” refers to specific wavelengths of [visible] light that artificial light sources — such as LEDs and compact fluorescents (CFLs) — emit.  These light sources lack many of the sun’s frequencies that our bodies and brains need, and yet, they amplify the amount of junk light they emit beyond what humans have evolved to handle. 

The wavelength ranges that cause the most concern includthe following: 

green light (492-577nm)  

blue light (455-492nm) 

violet light (400-455nm)

graph showing viable light spectrum
Source: Arch Lighting

Dave Asprey, the Father of Biohacking, coined the term junk light to emphasize the negative impacts that overexposure to blue, green and violet wavelengths can have on a person’s health and performanceHe says, “Junk light is worse than junk food; it’s the high fructose corn syrup of lighting.” In other words, exposing yourself to artificial junk light rather than natural sunlight or incandescent lightwhich is much warmer than the light found in LEDs and fluorescents, is akin to consuming spoonfuls of sugar versus a nutritious meal. 

The reason why junk light is arguably worse than junk food is because it has become so engrained in our everyday lives. In fact, studies show that the average American spends more than 92% of his or her time indoors under artificial lighting.  People are also getting more screen time than ever before, which means even more exposure to junk light via LED screens. Overexposure to artificial junk light, in turn, negatively impacts your energy, mood and performance.

office worker resting her face in her hands

How Does Junk Light Affect Your Health During the Daytime? 

Inside of our eyes are a class of light-sensitive eye cells, called ‘intrinsically photosensitive retinal ganglion cells’ (ipRGCs). These cells absorb light — especially blue light — in order to properly set our circadian rhythm in accordance with the rise and fall of the sunThat’s why when sunlight shines through your window each morning, your body temperature naturally starts to rise, and you begin to feel more alert. Conversely, when the sun goes down, the human body should naturally start to decrease in temperature and prepare to sleep. 

With that said, we are no longer solely relying on sunlight and fire like our ancestors. Numerous technological advances in lighting have led us to the world we now live in, where the lights are always on and our bodies don’t really know what time it is anymore.  

Think about it. The sun naturally changes its position in the sky throughout the day until it descends below the horizon at nighttime.  If you were outside during the day, your body would be exposed to different temperatures of light depending on where the sun was located at any given time.  However, since most people spend more time indoors then outdoors, we are now getting more exposure to artificial lighting than natural sunlight.  

graph showing wavelength of Sunlight, LED, incandescent and CFL blubs
Source: Calories Proper

Note that there is an inverse relationship between the wavelength of light (measured in nm) and the amount of energy that specific wavelengths contain. Light rays with longer wavelengths contain less energy, and those with shorter wavelengths have more energy. LEDs and fluorescents are notorious for emitting high levels of blue light (short wavelengths).

Overexposure to blue light can have several negative impacts on your health and performance during the daytime, such as: 

  • Lack of energy 
  • Digital eye strain 
  • Difficulty focusing 
  • Decrease in productivity 
  • Circadian rhythm disruption 
  • Greater risk of getting macular degeneration (the leading cause of blindness) over time

Unfortunately, most office buildings (where people spend 8-10 hours a day) are flooded with LEDS and/or fluorescents. Our gyms, grocery stores, airports and malls all use artificial light sources too. They look great for commercial purposes — and may even trick us into buying more! — but junk light does our health zero justice. 

couple in their 60's reading books in bed

How Does Junk Light Affect Your Sleep at Night?

Each night as the sun goes down, your body should naturally start producing more melatonin, which is the key hormone that your body needs in order to fall and stay asleep.  It also plays an important role in countering infection, inflammation, cancer, and auto-immunity (NCBI).  Of course, it’s much more difficult for your body to produce this hormone if the lights are still on, or if you’re constantly glaring at screens leading up to bedtime.  Many studies have shown that blue light suppresses melatonin productionwhich makes sense since wavelengths in this range promote alertness. 

Research has also suggested that green and violet wavelengths of light could potentially delay or disrupt your sleep, especially if they are used in the hours leading up to bedtime.

When you don’t get consistent, quality sleep at night, you’re at greater risk for many health issues, including but not limited to:

According to Matthew Walker, Neuroscientist and sleep researcher, “After just one night of only four or five hours’ sleep, your natural killer cells—the ones that attack the cancer cells that appear in your body every day—drop by 70%.”  Aside from putting your long-term health at greater risk, you’re also basically setting yourself up for failure tomorrow because you won’t be showing up as energetic, positive or productive as you otherwise would have if you had gotten a full 7-9 hours of sleep the night before. This sleep debt” can very quickly turn into a vicious cycle of feeling fatigued during the day and “wired and tired” at nighttime.

How to Stop Junk Light

Un-training your brain to turn the lights down or off may seem daunting, but it doesn’t have to be.  Here are some tips on how to prevent overexposure to junk light and protect your circadian rhythm: 

  • Maintain a routine schedule in which you wake up and go to bed at the same times every day. 
  • Get at least 20-30 minutes of natural sunlight every day (NCBI). 
  • Wear blue light blocking glasses during the daytime that block up to 75% of blue light* 
  • Wear junk light blocking glasses that are specifically designed to help you hack your sleep; they should block up to 100% of blue, green and violet wavelengths of light to help put your brain into an alpha (or meditative) state before bedtime. 
  • Use blackout curtains in your bedroom. 
  • Keep the lights dim in your house in the hours leading up to bedtime. 
  • Use Junk Light Dots (stickers) to cover up those pesky little power source lights that you often find on computer or tv monitors, or on appliances. 
  • Makes sure that you make room for 7-9 full hours of sleep every night.

*You don’t want to wear glasses that block more than 75% of blue light during the daytime because your body still needs SOME blue light in order to remain active and alert. 

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