Health, aging, and performance have quietly become things we track. We measure our steps, our sleep, our heart rate variability. Somewhere along the way, the tools we use to understand our bodies in real time went from novelty to normal. So when we sat down with Stacy Salvi and asked, “What Is The90?”, we realized it fills a gap almost nobody had thought to measure: the sunlight hitting your skin every single day, whether you notice it or not.
Here’s the part that isn’t obvious at first glance. The90 connects an environmental input, sun exposure, to long-term outcomes like skin aging and overall well-being. This isn’t a connection you can feel (or even notice) happening at first. Instead, sun exposure shows up later as cellular damage, photoaging, and an increased risk of sun cancer. However, that’s precisely the problem The90 was built to solve. That connection is not something you can feel happening. And that is precisely the problem it was built to solve.
Curious, Lauryn and Michael invited CEO and Co-founder of The90, Stacy Salvi, onto The Bossticks. You can listen to the full episode below for every single detail. But for now, we’re diving into what The90 is, how it works, and the unique benefits you can expect.
Before reading, it’s important to note that we are not doctors or dermatologists. We are simply sharing what we learned from an insightful conversation and what works for us. For any personalized medical advice, consult with your doctor.
What Is The90 and Why It Matters
So, what is The90? The90 is a personal sun intelligence system designed to help you understand and track your exposure to sunlight, then learn how that exposure affects your long-term skin health, aging, and overall well-being.
The90 is the first personal sun intelligence system designed to help women decode their real-time UVA and UVB exposure. Not only is it innovative; it can be genuinely helpful. With a preventative skin health wearable that measures UV exposure in real-time, the system allows women to take control of how they age.
The whole thing is built around one idea: sunlight plays a far bigger role in how we age than most people realize. And The90 is rooted in a powerful truth: up to 90% of visible skin aging, including wrinkles, fine lines, and sun spots, is caused by UV exposure, not chronological aging.
That statistic is exactly where the name comes from. It also reinforces the idea that sunscreen isn’t just a one-time morning habit; it’s something you need to consider throughout the day as your UV exposure changes.
As Stacy put it on the show, the goal is empowerment over fear. The sun isn’t the enemy. The point is knowing your real-world exposure so you can be strategic about it. You can hear the full breakdown in the Stacy Salvi podcast with The Bossticks.
Who Created The90 and Why It Exists
The90 was created by Stacy Salvi, a wearables veteran who spent years inside one of the biggest names in the category. Stacy Salvi previously led the acquisition of Fitbit by Google, and is a health expert when it comes to tech wearables. On The Bossticks, she shared that while she started her career in law, she later pivoted into tech. As if that wasn’t impressive enough. Stacy learned the engineering language herself when people told her she lacked the right background.
However, her passion for health runs deeper than a resume. She told Lauryn and Michael about a serious illness after her first year of law school that put her body into sepsis and left her hospitalized for nine days. That experience shaped how she thinks about staying balanced and staying healthy, and it drew her to wearables as a way to connect people with their own bodies.
But here’s the burning question: Why does The90 exist? Ultimately, it’s because the tools we already had weren’t measuring the thing that matters the most for skin.
Unlike the generic UV index, which provides broad location-based estimates, The90 Gem captures live UV data from the user’s actual environment and translates it into actionable sun intelligence. Stacy continued to tell Lauryn and Michael that her mission connects to research from Dr. Richard Weller, a dermatologist and professor at the University of Edinburgh, on how sunlight impacts overall health.
Stacy also told us her mission connects to research from Dr. Richard Weller, a dermatologist and professor at the University of Edinburgh, on how sunlight impacts overall health.
How The90 Sun Intelligence System Works
The90 Sun Intelligence System pairs a small wearable with a companion app. More specifically, paired with the The90 app, available now on Apple and Android app stores, the system tracks cumulative sun exposure, models sunscreen decay, and delivers personalized reapplication prompts based on your actual UV load.
Here is how each piece works.
Wearable or Tracking-Based Sun Exposure Monitoring
The device itself is a pendant, worn on a chain, and it is intentionally beautiful. On The Bossticks, Stacy told Lauryn and Michael she was “uncompromising about making technology hidden in jewelry.” In fact, the technology is only the size of a nickel, so people actually want to wear it.
If you haven’t watched the podcast episode yet, let’s break down what this means. Under her venture The90, Stacy launched the Gem wearable that looks like a stylish round necklace. On the inside of the wearable, there’s a built-in UV sensor to track the skin’s UV exposure in real time.
The more you wear it, the more you get out of it.
Measures UVA and UVB Exposure Levels
Here’s a beginner-friendly distinction Stacy taught us: UVA is the aging ray; UVB is the burning ray. The device reads both. The Gem wearable has a photodiode sensor that detects UVA, which is the aging UV, and UVB, which is the burning UV.
On the show, Stacy explained that UVA is under-counted because it comes through windows, hits you on short walks, and accumulates quietly over time. That means you may not be protecting yourself as much as you could be.
Converts Invisible Light Data Into Actionable Feedback
Sunlight data is invisible to us. The magic is turning it into something you can act on. The tracking features and the collected data run through algorithms that factor in your sunscreen and skin profile, then tell you what to do next.
Tracking both UVA and UVB rays, The90 Gem analyzes exposures against a personalized skin profile to deliver guidance on UV thresholds, sun exposure windows, and sunscreen reapplication timing. Depending on your exposure, the app may prompt you to apply or reapply sunscreen or suggest post-sun skin-care steps.
Provides Awareness of Cumulative Exposure Over Time
This is the heart of it. Most of us think about the sun on vacation, not while running errands or sitting in the car. On The Bossticks, Lauryn shared the moment she first understood incidental exposure, walking across a parking lot after a glycolic peel at nineteen and realizing all the little sun moments add up.
The90Gem helps prevent situations just like this. More specifically, it keeps a tab of the UVA and UVB data received from the sensors in real time. From there, it builds a personal skincare profile over time. and over time builds a personal skincare profile.
Benefits of Using The90 System
The value here is not vanity. It’s awareness, and awareness changes behavior. Here’s a closer look at the potential benefits of using The90 System:
Improved Awareness of Sun Exposure Habits
You can’t manage what you don’t measure. Stacy said awareness is the first step, and the device is designed to take decision fatigue away. No more guessing whether to reapply or head inside. You simply know. Even on a cloudy day in Austin, Stacy told listeners her device flagged that UV was extremely high, which most people would never suspect.
Better Understanding of Skin Aging Factors
Once you see how much UVA you are actually absorbing, the science clicks. Just as we mentioned earlier, up to 90% of visible skin aging, including wrinkles, fine lines, and sun spots, is caused by UV exposure, not chronological aging.
Stacy explained on the show that when UVA accumulates, it breaks down collagen and elastin and causes those dreaded sunspots. Understanding the “why” makes it much easier to protect yourself.
More Intentional Skincare and Lifestyle Decisions
Data lets you build a real strategy. That might mean tinting your car windows, choosing a rash guard, or timing your morning walks when the UV levels are low. As Lauryn shared, she wears a hat, gloves, and sunscreen when UV is high, then takes a circadian rhythm walk when it drops to zero. The sun is not off-limits; exposure should just be intentional.
Long-Term Health Optimization Mindset
When it comes to The90, there’s also a bigger-picture benefit: sunlight isn’t all bad. And the system makes sure to clarify this.
The app has a Vitamin D tracker that estimates how much more sun you need to reach your daily target. It also has an “Own Your Light Index” that rewards sun-protection habits like following a sunscreen plan. Even better? The90 Gem offers approximately 7 days of battery life just from one single charge, making protection easy.
Stacy told listeners that many of us are low in vitamin D because we live indoors under screens. That said, knowing when you have hit your target, without overdoing it, is a genuine health tracking win.
Interested in learning more about how to protect your skin from UV rays? Check out our post on tips for staying safe in the sun.
What Makes The90 Different From Fitness Trackers
Not Step-Based or Calorie-Based Tracking
Your typical fitness band counts steps, calories, and physical activity. The90 doesn’t chase movement metrics. Remember what we said earlier: The90 gets its name from the percentage of visible skin aging caused by the sun. Just like tracking sleep or activity with a wearable like the Oura Ring, the Gem uses a special sensor aimed at light, not laps.
Focuses on Environmental Exposure Instead of Movement
Instead of measuring what your body does, it measures what the environment does to your body. The device differs from conventional UV index data by measuring conditions in a user’s immediate environment rather than relying on location-based estimates. That’s a meaningful shift. While you and your neighbor may be in the same town reading the same UV index, your exposure is much different based on location.
Prioritizes Long-Term Biological Impact Over Short-Term Metrics
Most trackers reward today’s numbers. The90 plays a longer game. Driven by the ethos to “Own Your Light,” The90 empowers women to strategically harness the health benefits of sunlight while also protecting their skin for the long-term. The system essentially turns real-time UV exposure into personalized sun intelligence for smarter sunscreen timing, healthier skin aging, and a more balanced relationship with UV rays.
Stacy also sees a future where this data blends with other wearable data using artificial intelligence to reveal how the sun affects sleep, mood, and more.
How The90 Is Used Day to Day
This is the part most people miss: practicality. The more consistently you wear The90, the more accurate your insights become. Here’s how to incorporate it into a daily routine with ease:
Set Up The90 System and Activate Tracking
You start by downloading the app and pairing the Gem. This is, naturally, the most important step. Following this, the system is paired with The90 app, available on both Apple and Android app stores.
Establish a Baseline of Daily Sun Exposure Habits
Next, the device learns your skin. On the show, Stacy walked listeners through a 16-point questionnaire covering skin tone, eye color, how your skin responds after the first sunny day of the year, and some family history. She continued to say that while biology matters, using the example that lighter-eyes people tend to be more sun-sensitive, we’re not a monolith. (In other words, this isn’t universal.) This is exactly why the questionnaire is as in-depth as it is.
Monitor UVA and UVB Exposure in Real Time
Once you’re set up, the tracking runs passively as you go about your day. The90 captures live UV data and translates it, with Salvi stating “This is all about empowerment. We are celebrating healthy habits and really encouraging you through a gamified experience.” This real-time layer is the difference between guessing and knowing.
Review Daily and Weekly Exposure Patterns
After the system collects data, then you look at the trends. Reviewing your daily and weekly patterns shows you where your exposure is actually coming from, which is often not where you would guess. This is how the collected data becomes personal insight rather than raw numbers.
Identify High-Exposure Times and Environments
Patterns reveal culprits. Maybe it’s your commute, your desk by the window, or midday errands. On the show, Michael described getting “as red as a lobster” after just fifteen or twenty minutes at peak sun on vacation, a reminder that timing matters as much as duration.
Adjust Habits
Now you act. This is where awareness pays off. You might reapply sunscreen, throw on a hat or rash guard, tint a window, or shift your outdoor time to a lower-UV window. Small, informed adjustments compound.
Track Progress Consistently Over a 90-Day Period
Consistency is everything. Wearing it steadily over roughly ninety days gives the system enough real-world signal to calibrate to you. The90 Gem measures both UVA and UVB exposure throughout the day and uses that information to generate personalized UV thresholds, sunscreen reapplication reminders, and recommendations around sun exposure.
Evaluate your overall exposure trends and protect your skin with The90
At the end of the cycle, you step back and read the whole picture. Are you a sun seeker or a sun avoider? Are you getting enough for vitamin D without going overboard? Stacy told us the device calibrates over time to offer exactly these insights. Michael’s plan says it best: check your bloodwork, use the device for a few months, and see what changes. You can watch the full conversation right here on The Bossticks YouTube channel, and while you are there, subscribe so you never miss an episode!
If The90 speaks to you the way it spoke to us, you can learn more or shop the Gem directly at the990.com, where our audience gets $100 off. And if you want our full sun-smart routine, make sure to check out TSC Caffeinated Sunscreen, made with ingredients like zinc oxide, caffeine, and spirulina maxima.