Let's chat about this...

A couple weeks ago - one of my favorite blue blocking glasses companies (I have had their blue blockers since 2021 & LOVE them) released SUNGLASSES 🫣......and honestly you would have think they committed some sort of heinous crime the way that some people reacted.

Knowing the owner very well, and also attempting to see all sides of things - I held my tongue, and I did not make a public statement.

Now that the dust has settled a little bit, I want to talk about it - as well as create more long form content around what I call "responsible sun exposure" (stay tuned for that)

If you missed Thursday's email - I have a brand new 16 page ebook that is only available in Quantum Nutrition 2.0 currently (as a part of the SUNWISE module - which was released on Friday to everyone who owns Quantum Nutrtion!)

However - I am sharing it here with my subscribers out of appreciation for your continued support!

​Click here to download the brand new guide.

OK let's talk about sunglasses ⬇️⬇️

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Circadian sensing - metabolic sensing & skin protection..

Your eyes are circadian sensors—NOT just visual cameras.

There are special cells in your retina called ipRGCs (intrinsically photosensitive retinal ganglion cells).

Their job? To detect natural light—especially blue light in the 460–480nm range—and send signals to your suprachiasmatic nucleus (SCN), your brain’s master clock.

This light sets the rhythm for:

• Cortisol release
• Leptin sensitivity
• Thyroid function
• Insulin regulation
• Sleep quality (via melatonin timing)
• Skin protection

2. Blocking light = scrambling your metabolic clock.

When you wear sunglasses first thing in the morning—or any time when you’re outside and need that light cue—you’re essentially cutting off the signal.

Your body stays in bio-time limbo, not knowing if it’s sunrise, midday, or still night.

This leads to:

• Cortisol misfires
• Leptin resistance
• Poor sleep
• Increased appetite + fat storage

3. Sunglasses can contribute to light deficiency—just like staying indoors all day.

Most people already spend 90% of their day inside.

Then when they do go outside, they immediately throw on sunglasses—further muting the circadian message.

It’s like whispering to your hormones when you should be shouting “WAKE UP, it’s morning!”

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Flipping your metabolic switch with LUX

Sunglasses dramatically reduce total lux hitting your eyes.

Lux is a measure of light intensity (how much visible light is reaching a surface—in this case, your retina).

Typical sunglasses can cut incoming light by 75–95%, depending on the tint and polarization.

(This is why there is a Lux meter in MyCircadianApp - so you can understand your light environment from every angle!)

Why does that matter?

Because your circadian system—especially the ipRGCs that trigger hormone cascades—needs a minimum melanopic lux threshold to fire properly.

Many studies show you need at least 1,000–2,000 lux (preferably natural, full-spectrum) to kick off proper cortisol and clock gene signaling.

So if you’re wearing sunglasses during your key morning window, you might never hit the threshold, even if you’re outside.

2. It’s not just the amount—it’s the spectrum.

Sunglasses also filter out specific blue wavelengths (~460–480nm) that are essential for stimulating melanopsin.

Even if some light gets through, the circadian signal is muted or distorted.

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Sunlight entering your eyes early in the day helps your skin build its own protection.

How?

Because that same blue light signal that hits the retina and talks to your circadian clock also tells your skin to:

• Ramp up melanin production
• Activate DNA repair enzymes
• Generate protective compounds like histidine → urocanic acid (a natural UV filter)

It’s called anticipatory programming—your body prepares for UV before it even hits your skin.

But when you wear sunglasses all the time?

You block the signal.

Your skin gets caught off guard by UV light later in the day—because your brain never got the memo.

The result?

• Easier burning
• Poor tanning response
• Damaged collagen
• And long-term, it could contribute to more sun sensitivity and photoaging

A Case For Sunglasses (Yes, Sometimes They’re Necessary)

Before we toss every pair of sunglasses in the ocean, let’s get real: There can be situations where sunglasses are helpful—and even necessary.

Here’s when and why:

1. Glare causes retinal overstimulation.

Glare is intense, uncontrolled light—often from reflected surfaces like snow, water, glass, or even white sand (so think driving - skiing - on the water or walking on sand in the middle of the day).

This harsh light floods the retina, especially the fovea (the part responsible for sharp, central vision), and can lead to:

• Photostress: temporary vision impairment from overstimulation
• Reduced contrast sensitivity: harder to distinguish objects from backgrounds
• Eye strain and fatigue

2. Glare increases oxidative stress in the eye.

Just like skin, your retina is highly metabolic and vulnerable to oxidative damage from excessive light exposure—especially in the blue and high-energy visible (HEV) spectrum.

Studies show intense glare can increase free radical production in the eye, overwhelming antioxidant defenses like lutein and zeaxanthin, and accelerating macular degeneration over time.

3. Glare activates the sympathetic nervous system.

Harsh light can trigger a stress response—pupillary constriction, tension in the facial muscles, and even headaches or dizziness.

This response increases cortisol and pulls you out of parasympathetic (“rest and digest”) mode, which is not ideal if you’re trying to regulate hormones, mood, or digestion.

4. Glare can dangerously impair visual processing—especially while driving.

This is a common cause of car accidents, particularly in older adults whose eyes are more glare-sensitive due to lens changes and slower pupillary response.

Protective sunglasses reduce:

• Photostress and blue light overload
• Risk of temporary “white-out” vision loss
• Long-term retinal damage
• Nervous system activation in high-glare situations

Glare isn’t just annoying—it’s biologically stressful.

Use sunglasses strategically when:

• Light is reflecting off water, snow, or pavement
• You’re driving toward the sun

And don't forget to protect your skin in these situations also!

As for me - I am almost never in these situations - so you likely won't find me in a pair of sunglasses (and will never find me in sunglasses while sunbathing).....BUT - it's important to see all sides of things when you are speaking to a large - international group that you respect (like my newsletter readers ❤️🙏).

There are 2 brands I can recommend, because they have gone above & beyond to ensure that the important wavelengths of blue are not filtered out:

​RA optics blue sync - use code SARAH​

​Bon Charge - use code SARAHK​

Stay tuned for more content in the coming weeks on responsible sun exposure & make sure to take advantage of all the amazing content in Quantum Nutrition 2.0 (including SUNWISE) - if you want to use light and nutrition to have optimal health year round!