ben greenfield

Everything You Need to Know About How Light Impacts the Human Body with Matt Maruca – Ben Greenfield Fitness

Check out the Ben Greenfield Fitness Episode Page & Show Notes

Key Takeaways

  • The Facts
    • In addition to the eyes, humans have photoreceptors on their skin
    • Excessive exposure to LED lighting in computers and smartphones is damaging to the eyes
    • Immune system function is impaired with low levels of vitamin D
    • “Not going into the sun is absolutely a serious form of malnutrition”
    • “Living indoors and looking at a computer under fluorescent lights all day is harmful to your body. You can’t out-diet and out-supplement that.”
    • Rates of chronic disease and mental illness are though the roof
      • Mitochondrial dysfunction seems to be at the core of this disease epidemic (and light is at the heart of how to enhance mitochondrial function)
  • Light Biohacking Tactics
    • When choosing an LED bulb, select one with a color rendering index (CRI) of > 97 and a color temperature <3000K
    • Light your house with candles or red incandescent bulbs at night to avoid inhibiting melatonin production due to excess blue light exposure 
    • Get as much morning sunlight as possible
    • Wear blue light blocking glasses at night
    • At night, put your iPhone into “red light mode” – here’s how
    • Use Iris Tech on your computer (it’s superior to f.lux)
    • For the most part, avoid wearing sunglasses
  • Matt’s Light Diet Protocol
    • Sleep and wake with the sun
    • Bathe in morning light
    • Get as much sunlight during the day as possible 
    • Consume fatty seafood
    • Drink clean spring water
    • Bathe in cold water
    • Avoid man-made electromagnetic radiation

Products Mentioned

Books Mentioned


  • “Light affects your biology. Light is one of those visible, yet sometimes invisible, variables that drastically affects things like your mitochondria, ATP production, sleep, wound healing ability, skin health, and elastin/collagen production.” – Ben
  • This episode is a two-parter: the first half features a discussion from Ben, and the latter half consists of a lecture from Matt Maruca (@thelightdiet) of RA Optics

The Impact of Light on Human Biology

  • Artificial light can damage overall health & wellness
    • Excess exposure reduces endocrine/cellular function, disrupts sleep/circadian biology, allow for mitochondrial dysfunction, and increases risk of both cancer and heat disease
    • There are a host of recent studies linking artificial light to breast cancer
  • Exposure to artificial bright light (LED lighting) at night suppresses melatonin secretion and increases sleep latency (the time it takes you to fall asleep)
    • It also increases alertness (which could be beneficial if you’re trying to keep yourself awake)
  • Excessive exposure to LEDs increases the risk of cataracts and age-related macular degeneration
    • Why are LEDs so harmful to the eye?
      • In color-changing LED systems (like a smartphone), the intensity of the three color sources (red, green, and blue) has to be changed to achieve the different colors. With color changes, the method is such that the LEDs have to rapidly alternate between full intensity and switching off over and over again (this causes “flicker”).
        • Our retinas perceive this flicker (even though we’re not conscious of it, it can be observed with something like a slow-motion video recording on an iPhone)
        • Flicker results in irreversible damage to the photoreceptor cells in the eye. This causes headaches, poor eyesight, brain fog, lack of focus, sleep disruption, etc.
  • Energy-saving fluorescent lighting causes similar issues to the above
    • This type of light causes oxidative stress damage not only to the eyes but to the photoreceptors spread out across the skin (this has a downstream effect of hormone/endocrine system disruption)

Light for Healing

  • Check out The Influence of the Blue Ray of Sunlight
    • The author discusses the influence of the sun on the restoration of health from acute & chronic disorders
    • Also, check out Principles of Light and Color
  • The man who won the Nobel Prize for physiology in 1903 used red light to treat smallpox and other light spectrums to treat chronic disease states like tuberculosis

Light Affects Metabolism

  • Plants and humans grow more in the summertime due to light’s increased activation of mTOR
    • “If you’re in a constant stage of light exposure, like many folks are these days, even when sleeping, your hormones and metabolism shift towards constant mTOR activation, growth, and anabolism. This is generally associated with things like cancer and a shortened lifespan.”

Light Biohacking Tactics

Use Healthy Light Bulbs

  • Look at a light bulb’s color rendering index (CRI) – the measurement of a light source’s ability to reveal the colors of various objects accurately in comparison with natural light
    • Sunlight’s CRI = 100
    • When choosing an LED bulb, select one with a CRI of 97 or higher
  • Also, look at a light bulb’s color temperature (measured in Kelvin (K))
    • That of the sun = 5500K
    • Many LEDs have a color temperature > 6500K
      • When choosing LED bulbs, make sure they have a color temperature <3000K
  • Make sure the LED bulbs you’re using are “biological LEDs”
    • Lighting Science is a good brand – they make bulbs that give off light in specific wavelengths that complement your circadian rhythm
      • Lighting Science makes a Sleepy Baby Bulb and a Goodnight Sleep Bulb which both emit lower levels of blue light (and because of this, don’t interfere with melatonin production)
        • They also make a GoodDay Bulb that produces more of a “natural morning sunlight” type of light
  • All this being said – avoid LED bulbs for the most part
    • Ben mostly has clear incandescent bulbs (with a color temperature of 2700K) in his house with a few red incandescent bulbs in his bedroom
      • He’ll also just use a candle for light at night if he can 

Get as Much Morning Sunlight as Possible

  • There are SO many benefits to a 30-60 minute walk in the sunshine as soon as you wake up
    • “It’s just an incredible way to begin your day”
    • The most significant benefit: you’re getting full-spectrum light that helps to regulate your circadian biology
  • If you’re deficient in the fat-soluble vitamins D and A, your photoreceptors become less sensitive to sunlight
    • Eat a diet rich in fatty acids to provide yourself with ample amounts of vitamin D and A (this will enhance the effects of the morning sun)

Block Blue Light at Night

Avoid Artificial Light in the Morning (and at night)

  • Why? – It’s not full-spectrum light (hence it messes up your circadian rhythm)
  • If you can’t get outdoors, use red/near-infrared light panels (like the Joovv) (this simulates sunlight)

Expose Yourself to Red Light in the Evening

  • Use candles or red incandescent bulbs to light your home at night
  • Also, put your phone in “red light mode” – here’s how

Install Iris Tech on Your Computer

  • It’s superior to f.lux
  • Iris:
    • Controls the brightness (or Kelvin) of your monitor
    • Reduces flicker
    • Allows you to adjust the font to be more eye-friendly
    • Allows you to optimize screen pulsations, thus reducing eye strain
    • Allows you to switch your monitor to “paper view” (like a Kindle)

Use an Anti-Glare Computer Monitor

  • Why? – Most monitors are backlit with LEDs (which we know are harmful) 
  • Ben uses the Eizo Flex Scan monitor 

Use LightDims

  • They’re light-blocking stickers you can use to cover up LEDs on electronics 
  • Even if you use a sleep mask, there are light-sensing photoreceptors on your skin
    • This is why going out in the sun during the day is so beneficial to your circadian rhythm – expose as much skin as possible!
    • But if you are going to get a sleep mask, we’re loving the Manta. It even has cooling rings for your eyes. Code PODCASTNOTES15 for 15% Off.

Install a Drift Box on Your TV

  • It blocks a lot of the blue that TVs emit (allowing you to watch it at night)

Avoid Overusing Sunglasses

  • You’ll hardly ever catch Ben wearing them during the day
  • When you wear sunglasses, you actually have a higher risk of getting a sunburn. Here’s why:
    • Sunlight stimulates the pituitary gland via the optic nerve in the eye
      • This signals to the body to produce a hormone that triggers melanocytes in your skin to produce more melanin (which protects the body from UV radiation)
      • When you wear sunglasses, less sunlight reaches the optic nerve

Use Photobiomodulation as Much as Possible

  • The Joovv is a light therapy (photobiomodulation) device which gives off red and near-infrared wavelengths of light
  • Red and near-infrared wavelengths of light help your cells become more efficient at producing energy
    • This results in a laundry list of benefits – hair regrowth, muscle recovery, weight loss, better skin, enhanced cognitive function, reduced symptoms of depression, enhanced cell signaling, enhanced clearing of metabolic waste, as well as increases in testosterone for men and increases in estrogen for women
  • But realize, more is not always better when it comes to red/infrared light therapy
    • Infrared light dissociates nitric oxide from a part of the electron transport chain called cytochrome C oxidase – if you do this too much you can create excess oxidation and free radical production
  • How far from your body should red light therapy devices, like the Joovv, be?
    • “Typically with a red light therapy device that has a power of ~100 mW/cm^2 [like the Joovv), you can get all the benefits you need in about 5-15 minutes if you are 2-6 inches away from the device”

Enter Matt Maruca

Setting the Stage

  • Mitochondria are the cellular engines which power many of the body’s functions – each cell contains thousands of them
    • Mitochondrial function isn’t so much controlled by food, but more so by light
  • The common thread among all the modern chronic diseases (obesity, diabetes, heart disease, Alzheimer’s disease, and cancer) is dysfunctional mitochondria within the diseased tissue
  • The human body requires fuel (food), oxygen, and a spark (light) to ignite the process of metabolism
    • Vitamins won’t solve the problems caused by a lack of the appropriate wavelengths of light necessary to complete metabolism
  • Rates of chronic disease and mental illness are though the roof
    • Mitochondrial dysfunction seems to be at the core of this disease epidemic (and light is at the core of how to enhance mitochondrial function)

The Horrors of Working Under Fluorescent Light

  • A 1980 study found that the incidence of malignant melanoma (skin cancer) was considerably higher in office workers who were regularly exposed to artificial light compared to people who work outdoors
  • Skin cancer rates have skyrocketed since 1900, yet most people work indoors
    • In 1900, 75% of people worked outdoors
    • In 1970, <10% of people worked outdoors
    • Today, it’s even smaller
  • “The amount of disease and death caused by avoiding sunlight is orders of magnitude greater than the amount of melanoma caused by sunlight”

How Sunlight Affects the Body

  • “Not going into the sun is absolutely a serious form of malnutrition”
  • Ultraviolet (UV) light from the sun:
    • Activates the synthesis of vitamin D (which is a prerequisite for the absorption of calcium and other minerals)
      • When people have higher vitamin D levels, risk for every type of cancer is decreased
      • “The immune system doesn’t function optimally with low vitamin D levels”
    • Lowers blood pressure by stimulating the release of nitric oxide from our blood vessels causing them to vasodilate (expand)
    • Increases the efficiency of the heart (AKA cardiac output)
    • Improves EKG readings and blood cholesterol profiles 
      • Cholesterol tends to be broken down by UV light – this allows us to make the molecules which are derivatives from cholesterol more easily (i.e., sex hormones and vitamin D)
  • Vitamin D is only one of countless molecules in the body affected by sunlight
    • Sunlight affects: the production of sex hormones, dopamine, melatonin, and serotonin
  • A lack of sunlight results in:
    • Hypoglycemia
    • Lowered basal metabolic rate
    • Decreased sperm potency
    • Feelings of depression
  • Sunlight has been found to increase the oxygen content of blood and the capacity of the body to deliver oxygen to tissues
  • Sunlight exposure increases white blood cell count (which help the body defend against infections)
  • Studies show that a 1-hour walk outside (even when it’s cloudy) can alleviate systems of seasonal affective disorder

Light & the Circadian Rhythm

  • For more on the circadian rhythm, check out these Podcast Notes with Dr. Satchin Panda
    • Also, check out Satchin’s book – The Circadian Code
    • In short, we need sunlight to regulate our circadian rhythm
    • Key takeaway: avoid eating late into the night
      • Sleep is a time for repair & regeneration – you want to avoid taking in substances that the body needs to burn
      • “I recommend not eating after 5 PM given the research”
  • Light coming into the eyes regulates the hypothalamus which in turn regulates the autonomic nervous system, energy balance, heat regulation, sleep, circulation, cell growth and maturation, and emotional balance
    • The hypothalamus also controls pituitary gland secretions (thus, melatonin production)
      • Melatonin is a hormone that, most importantly, signals to the body it’s time for bed (exposure to artificial light hinders its secretion)
  • The circadian rhythm controls many things, from the timing of hormone release to the need to poop in the morning

Matt’s Light Diet Protocol

Sleep and Wake With the Sun

  • (Go to sleep shortly after sunset and wake up as close to sunrise as possible)
    • “This is how we evolved to function, and it’s the only way our hormones and biological systems can function as designed”
  • Steps to facilitate this:

Bathe in Morning Light

  • Watch the sunrise (AKA expose yourself to the inclining light)
    • You can look directly at the sun for the first 10-15 minutes after it rises (this is known as sun-gazing)
    • While watching the sunrise, avoid wearing sunglasses or contacts (they block necessary UV light)
    • Even on cloudy days, there are benefits to being outside when the light comes up

Live Outdoors During the Day

  • Do what you can – try to get as much natural light as possible throughout the day 
    • If you work indoors, open the windows
  • “Living indoors and looking at a computer under fluorescent lights all day is harmful to your body. You can’t out-diet and out-supplement that.”
    • “Indoors used to be a place where we’d just sleep, not where we’d spend our whole day cooped up in a cave”
  • It takes ~10x the sun exposure time for the darkest skin types to synthesize the same amount of vitamin D as the lighter skin types
    • We generate the most vitamin D when exposed to the sun between the hours of 10 AM and 2 PM
  • “It’s okay to be pale in the winter but inexcusable to be pale in the summer; people with red hair might be the only exception.”

Consume Fatty Seafood

  • What specifically?
    • Sardines, wild-caught Alaskan salmon, anchovies, and mackerel
    • Avoid high mercury sources like tuna and swordfish
  • The DHA in these foods is beneficial for the eyes and brain in many ways, thus improving our ability to take in and store light

Drink Clean Spring Water

  • Chemicals like fluoride and chlorine in tap water prevent the water in our cells from storing as much light as possible
  • Find a spring near you here

Bathe in Cold Water

  • This allows you to assimilate more light by cooling your skin temperature
    • Not to mention, there’s a TON of other benefits to cold exposure

Avoid Man-made Electromagnetic Radiation (EMFs)

  • How?
    • Avoid living in a major city (most important)
    • Put your phone in airplane mode at night and while it’s on your body
    • Avoid bluetooth headphones/devices
    • Use an Ethernet connection instead of Wi-Fi
  • How is this relevant?
    • EMFs stress our mitochondria
  • Products:
    • Use the DefenderPad when using your laptop on your lap to reduce the EMF exposure your sexual organs are getting
    • To measure EMF levels in your home, use a Cornet ED88T EMF/RF Detector
      • Make sure your sleep space has low EMF levels

Additional Notes

  • Nearly 90% of kids during the Industrial Revolution had some sign of Ricket’s disease thought to be caused by a lack of vitamin D
  • In 1903, Niels Finsen discovered that UV light from the sun killed bacteria responsible for tuberculous of the skin
  • Most sunscreens are loaded with carcinogenic chemicals
  • “Ending relationships with bad and toxic people is probably the number one change you can make; it can’t be understated”
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