TrueDark Research Shows Light has Huge Impact on Circadian Rhythms

Research Shows Light has Huge Impact on Circadian Rhythms


Natural rhythms of life are happening all around us — daily, seasonally and annually. Birds, for example, chirp in the morning, bears come out from hibernation in the spring, and humans have a tendency to feel “blue” during the winter months.  

 All living things, from bacteria to humans, have a biological clock, or circadian rhythm, that inherently knows what time of day or year it is based on the inputs it receives. Light is one of the most influential inputs on circadian rhythm and essentially provides human and animal genomes  with precise blueprints for optimal performance throughout the day (and night).

A mother bear and her cubs embracing spring time after months of hibernating.

From Plants and Animals to Humans

Researchers began studying biological rhythms in the 1950s.  They have since credited protein-signaling as the secret to plants’ internal clocks. These proteins (Zeitlupe and FKF-1) contain certain amino acids that make chemical bonds in different levels of sunlight, thereby making specific parts or functions of a plant more active during the day while others are more active during the evening time.  Scientists have also identified that like plants, animals and humans also have biological clocks that prioritize specific processes throughout a 24-hour cycle that encourage optimal health.

The synchrony of an organism with both its external and internal environments is critical to an organism’s well-being and survival; without it, the organism may not survive. For example, nocturnal rodents don’t venture out from their burrows during broad daylight because then it would be too easy for other animals to prey on them.  Similarly, disruptions to your natural 24-hour internal cycle (like when you get jet lag, do shift work, and are sleep deprived) can lead to a variety of health problems within the individual, such as weight gain, risk of heart disease, dementia, high blood pressure, and a weakened immunity.

Timing is Everything

The bottom line is that plants and animals depend on Earth’s daily light/dark cycle in order to carry out life-sustaining behaviors, including but not limited to reproduction, sleep and protection from predators.

Consider the saying, “The early bird gets the worm”.  We often use this idiom to mean: if you do something early or before anyone else, then you will have an advantage and be successful. From a bird’s perspective, this is not only true but necessary, especially for the males.  Birds chirp to communicate, and it’s the males that sing as the sun rises in the morning in order to announce to potential mates that they are awake, alert and on guard to defend their territory. It is the morning daylight that prompts birds, other animals and humans to wake up and carpe diem! The descension of the sun and diminishing light help induce the rest that’s needed to repeat the cycle again the following day.

Everything in the World’s Ecosystems are Connected

It’s hard to imagine that at one time humans relied solely on the light of the moon, the stars and fire to see at night. It makes sense then that humans would rest as the sky turned dark and subsequently rise when the sun ascended into the sky again. Both people and technology have since evolved to prolong the number of hours that we stay awake each day. We now have an overabundance of artificial light — in our offices, our homes, at grocery stores and gyms — that constantly affects our internal environments and disrupts our circadian rhythms.

Birds migrating, relying on natural light to help them get to their destination.

Animals and insects suffer from light pollution too.  Birds, for example, die by the millions every year from colliding with illuminated buildings and towers.  When birds migrate or hunt at night, they rely on moonlight and starlight to navigate the skies. Artificial light can through them off course and even  can cause them to migrate too early or too late. This in turn means that the birds will miss ideal climate conditions for things like nesting and reproducing.

“When we add light to the environment,

that has the potential to disrupt habitat,

just like running a bulldozer over the landscape can.”

— Chad Moore, formerly of the National Park Service

Many insects are notably also drawn to light; artificial lights can cause declining insect populations, which negatively impact entire food webs that rely on insects for food or pollination.

What You Can do to Make a Difference

Be mindful of the lights that you use in and around your home. Remember that the blue light spectrum is the spectrum that causes disturbances to circadian rhythms of both humans and people. Opt for red bulbs when installing light fixtures around your driveway, front porch and backyard because red light encourages wildlife(and domesticated animals) to stay true to their daily sleep/wake schedule and causes no disruption to their life-sustaining behaviors.

When it comes to your personal circadian rhythm, notice how much time you spend in front of devices that emit blue light (TVs, computers, tablets, mobile phones, etc.) and under artificial light. Malls, grocery stores, airports and gyms are notorious for using junk light to intentionally alter human behavior; the light in malls makes you feel alert and want to purchase more things, for example. Invest in your own health by taking control of the light in your environment; get the right amounts of the right types of light at the right times of day.

TrueDark® offers a 24-hour solution to help you do just this. Our daytime glasses use yellow lenses to  filter out not too much but just enough junk light during the day — keeping you alert enough to function and do your work while preventing overexposure to artificial light. (Orange lenses block too much blue during the day and not enough of it at night.) Our night time glasses use red lenses to block out the entire blue-green-violet spectrum of light. Again, red plays an important role, especially at night, because it induces your mind and body into an alpha state — giving you the quantity and quality of sleep that nature intended for you to have.

Junk Light, Disrupted Sleep, and Your Health

Exposure melatonin disrupting junk light can have have effects on many aspects of your health

Sleep cycle disruption

Junk light exposure when traveling can disrupt your circadian rhythm. Long-term exposure to light at night which accompanies shift work is listed as a probable carcinogen by the World Health Organization. Light at night has shown to be highly associated with significantly the risk of hormone specific such as cancers of the breast and prostate.


The flickering wavelength of light associated with LEDs and compact fluorescent lights emit blue light that inhibits melatonin production but also create a unique glare that impacts your retina causing eye strain, headaches, and physical and mental fatigue.

Weight Gain

Red light and darkness move leptin and ghrelin into patterns that are (context dependent) associated with less hunger, while blue light does the opposite and can move both into patterns associated with more hunger.

Anxiety/Depression & Depression

Increase in cortisol, the stress hormone, due to circadian disruption. Memory recall is impaired with consistent sleep deprivation and may leave you distracted and not performing your absolute best.

layers of the eye

The Importance of Melanopsin Cells

The Key to Better Sleep

detects blue light

The melanopsin cells detect blue light it tells your brain that it is “daytime” and less melatonin is produced.

sending signals to your brain

The signals to your brain to alert brightness and for the brain to increase or suppress the sleep hormone, melatonin.

Light Source

Melanopsin cells can’t differentiate the blue light that occurs naturally form the sun from the junk light emitted from your computer monitor.

Start Optimizing Your Life

Harness Your Biology to Fight Junk Light

Your body requires some blue light at the right time of day and from the right sources. That’s why we created TrueDark® Sleep Technology that gives you 24-protection from junk light day and night.

Use TrueDark® Twilights When You’re Ready for Sleep

Stop Junk Light with TrueDark® Twilight technology that frees your hormones and neurotransmitters to do their best work.

When the sun goes down, blue light isn’t the only junk light that can disrupt our sleep cycle and more than blue blockers are needed. TrueDark® Twilight is the first and only solution that is designed to work with melanopsin, a protein in your eyes responsible for absorbing light and sending sleep/wake signals to your brain. Without melanopsin, melatonin can’t be accessed.

When you wear your Twilights for as little as 30 min before bed you prevent your melanopsin from detecting the wrong wavelengths of light at the wrong time of day. This supports  your circadian rhythm and helps you fall asleep faster and get more restorative and restful sleep.

TrueDark Twilights Classic glasses
TrueDark Daylight Elite glasses

TrueDark® Daylights for Your Waking Hours

The highly advanced lenses in TrueDark® Daylights operate on a more advanced level than traditional blue blockers.

Blue light emitted from the sun helps regulate our sleep/wake cycle. However, in today’s world, we’re exposed to an overabundance of blue light, or junk light from artificial light. This includes hours spent in front of  TVs, phones, and computers. It also includes time spent in artificial man made light with LEDs and fluorescent lights. Even if we’re simply reading a book, we’re doing that in artificial light which emit dramatically more blue light than the sun. That overexposure to junk light during the day has a dramatic impact on our neurotransmitters and hormones that are responsible for quality sleep.

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