Q: What is junk light? 

A: Junk light refers to artificial light sources – such as LEDs, compact fluorescent (CFLs), or any device with an LED screen (computers, smartphones, tablets, and laptops). These light sources amplify the blue, green and purple parts of the light spectrum. Your body’s natural sleep-wake cycle, also known at your circadian rhythm, is incredibly sensitive to these particular wavelengths. When exposed to any of them at the wrong time of day or night, you end up with junk light, which can directly impact your sleep, mood, focus, and cognitive function. 


Q: What is your “circadian rhythm”? 

A: Your circadian rhythm, also known as your sleep/wake cycle, is an internal clock that cycles between sleepiness and alertness at regular intervals over an approximate 24-hour period.  

This cycle – comprised of a “master clock” that orchestrates many other smaller clocks – is important for regulating various processes throughout your body, such as knowing when to wake up in the morning, when to eat, and when to sleep at night. The master clock is located in the suprachiasmatic nucleus (SCN), and the primary cue is the light–dark cycle, around which most mammalian (and those of all living organisms) functions have evolved (NCBI). 

The SCN is notably located in the hypothalamus within the brain, where the neurons have a dedicated link to the eye. So any time there is a change in environmental lighting, information enters the eye and is directly transferred to the master clock. The SCN then influences daily rhythms in your sleep-wake cycle, hunger-satiety, body temperature, and hormone levels. 

Q: Why is it so important to maintain your natural circadian rhythm? 

A: When your master clock is in sync with the natural rise and fall of the sun – meaning that you are awake and alert while the sun is up, and you’re sleeping while the sun is down – it can effectively communicate this regulatory information to the rest of the body. This helps your body carry out natural processes, including but not limited to: hunger, thirst, sleep, body temperature, and hormone levels. 

Q: How does junk light affect your health? 

A: Junk light impacts photoreceptor cells in your eyes, which can disrupt the communication that happens between your eyes and your brain. This is especially problematic at night time because junk light suppresses your body’s ability to produce melatonin, the sleep hormone that you need in order to fall and stay asleep.  Junk light also emits a unique glare that impacts your retina, which can cause eye strain, headaches, as well as mental and physical fatigue. 

Junk light may contribute to and, or be linked to many chronic health conditions, including but not limited to: 

  • Eye strain 
  • Headaches 
  • Brain fog 
  • Short-term memory loss 
  • Problems sleeping, due to melatonin suppression 
  • Stress and anxiety, due to cortisol suppression 
  • Symptoms of Seasonal Affective Disorder or depression 
  • Endocrine disruption and a poor immune system 
  • Female hormonal/menstrual cycle disruption 
  • Weight gain 
  • Agoraphobia (anxiety disorder) 

Because overexposure to junk light is so closely linked to sleep deprivation, it can indirectly have other long-term impacts on your health, such as: 

  • Heart disease 
  • Diabetes 
  • Mood disorders 
  • Cancer 
  • Alzheimer’s* 

*Insufficient sleep can lead to an increased development of a toxic protein in the brain called beta-amyloid that is associated with Alzheimer’s disease. When we sleep, the brain naturally cleanses itself of this toxic protein, but when we offset sleep the brain is unable to carry out this process effectively. (Business Insider

Q: Who came up with Stop Junk Light Day and how do I get in touch?
A: #Stop Junk Light Day and #StopJunkLight were created by TrueDark to educate people about the harmful effects of artificial lighting, and to empower people to take more control over the light in their environment for healthier living.
Q: How do I get in touch with someone from TrueDark to discuss things like media inquiries, speaking opportunities, and collaborations?
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– Or send an email directly to: info@stopjunklight.org
– Or send us a private message on Facebook, Instagram, or Twitter