That's a lot, I know. Pick the piece that resonates and ignore the rest!
And in case you missed my latest Substack Article - check it out below!
I just dropped a new article on Substack breaking down the full mechanism, but I want to give you the most important pieces right here, because this is something most people have never heard and it changes a lot once it clicks.
Your eyes aren't just for seeing. They're circadian sensors.
There are specialized cells in your retina (called ipRGCs, if you want to nerd out) that detect natural light and signal your brain's master clock. That clock then tells your cortisol, leptin, thyroid, melatonin, and even your skin what time it is and what to do.
When you put sunglasses on during the day, you're filtering out 75 to 95 percent of that signal- Your brain still gets a message, it's just a much weaker one.
The cloudy day twist that surprised me most:
On a sunny day, you have so much light intensity that even with sunglasses you might still hit your circadian threshold. But on a cloudy day, when you're starting at much lower lux levels, sunglasses can drop you below threshold entirely.
Meaning you're functionally getting indoor-level light at your eye, despite being outside. Your body has no idea it's daytime.
The argument for ditching sunglasses actually gets STRONGER on cloudy days. Wild, right?
Here's the part that blew my mind:
When light hits the back of your eye, it triggers a hormonal cascade through your pituitary that releases something called alpha-MSH. This hormone helps coordinate appetite regulation, immune function, AND your skin's ability to protect itself from UV.
Translation: what your eye sees directly impacts what your skin can do to defend itself. There's research showing that when light is blocked at the eye, the skin's natural protective response is suppressed.
This is the mechanistic explanation for something a lot of people notice but can't explain: they actually burn MORE easily when they wear sunglasses outside than when they don't.
The dependency loop nobody talks about:
Wearing sunglasses regularly can make your eyes more sensitive to sunlight over time, not less. Your photoreceptors are designed to adapt to your light environment. When you filter natural light chronically, your eyes stay in a more "light-naive" state, which means natural light feels harsher every time the glasses come off.
Most women I work with assume they just have sensitive eyes. What they actually have are eyes that have never been given the chance to build a normal relationship with natural light.
That was me for years. After about 2 weeks of gradual bare-eye morning exposure, my eyes adjusted and I got my first real tan in years.
Read the full article here for the practical step-by-step, the nuance around when sunglasses ARE the right call, the big mistakes I see, and all the study citations.
I am also holding a free webinar on May 21st to dive deeper into safe sun exposure - sunglasses - vitamin D and more! Click here to register!
