Sunlight, UVB & Vitamin D: Benefits for Hormones, Mood & Health
Could spending so much of our lives indoors be affecting our hormones, mood, metabolism, sleep and vitamin D levels?
In this episode of The Hormone Solution, I sit down with Gerardo Gutierrez, better known as Guti, to talk about something incredibly simple that many of us may not be getting enough of: natural sunlight.
Guti shares his personal experience with low testosterone, depression and low vitamin D and how it led him down a rabbit hole researching sunlight exposure, UVB light, red light therapy, infrared light, circadian rhythm and hormone health.
And this conversation goes way beyond vitamin D.
We break down the different wavelengths of sunlight, why UVA and UVB are not the same thing, why infrared light matters, how the angle of the sun changes the light reaching your body and why people living in northern climates may struggle to get adequate UVB exposure during much of the year.
What Are the Health Benefits of Sunlight?
Sunlight is made up of several different wavelengths of light that interact with the body in different ways.
In this episode, we discuss how natural light may influence:
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Vitamin D production
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Circadian rhythm
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Sleep-wake cycles
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Mood and serotonin
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Hormone signaling
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Testosterone
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Metabolism
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Mitochondrial function
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Nitric oxide production
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Immune function
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Skin health
One of the biggest takeaways from our conversation is that the benefits associated with sunlight may extend beyond vitamin D alone.
What Is the Difference Between UVA, UVB and Infrared Light?
Not all sunlight is the same.
Guti breaks sunlight into three major categories:
Visible light is the portion of sunlight our eyes can see and plays an important role in signaling time of day to the brain.
Infrared light is invisible but is experienced as warmth. Infrared and near-infrared wavelengths are also used in many red light therapy and photobiomodulation devices.
Ultraviolet light includes UVA and UVB.
UVA vs. UVB
UVA light is strongly associated with tanning and photoaging and can also influence nitric oxide production.
UVB light is the wavelength responsible for stimulating vitamin D production in the skin. It is also the wavelength more associated with sunburn when exposure becomes excessive.
This distinction matters because the amount of UVA, UVB and infrared light available changes throughout the day and throughout the year.
What Time of Day Is Best for Sunlight?
The type of sunlight reaching us changes depending on the angle of the sun.
Guti explains that early-morning and late-day sunlight contain proportionally more infrared light, while meaningful UVB exposure generally becomes available when the sun is much higher in the sky.
That means morning sunlight and midday sunlight do not provide exactly the same signal to the body.
Morning outdoor light is particularly important for helping establish a healthy circadian rhythm, while midday sunlight is generally when UVB availability is greatest.
Can You Get Vitamin D From the Sun in Winter?
Not always.
This is especially important for women living in places such as Canada, the northern United States, the UK and northern Europe.
As the sun sits lower in the sky during winter, substantially less UVB reaches the Earth's surface.
That means you can go outside, see sunlight and still receive very little of the UVB required for meaningful vitamin D production.
For those of us living in northern climates, this was one of the most fascinating parts of this conversation.
Is UVB the Same Thing as Vitamin D?
No.
UVB light stimulates vitamin D production, but Guti argues that many of the health effects associated with sunlight cannot necessarily be explained by vitamin D alone.
We discuss research investigating whether some of the benefits observed in people who receive regular sunlight may involve UVB exposure itself and other biological pathways triggered by light, rather than simply increasing a vitamin D blood level.
This is one reason sunlight exposure and oral vitamin D supplementation should not automatically be considered biologically identical.
Can Sunlight Affect Hormones?
This is where the conversation gets especially interesting for midlife women.
Light is one of the body's strongest environmental signals.
The timing and type of light we receive influences our circadian rhythm, which in turn interacts with sleep, metabolism and hormone signaling.
Guti also shares his personal experience of increasing his testosterone after making several lifestyle changes, including increased sunlight exposure, exercise and better sleep.
Importantly, his experience involved multiple lifestyle changes, so it does not prove that sunlight alone increased his testosterone.
But it opens up a fascinating discussion about the relationship between sunlight, testosterone, ovarian hormones, vitamin D and hormone health.
What Does Morning Sunlight Do for Circadian Rhythm?
Your eyes contain specialized light-sensitive cells that help tell your brain whether it is daytime or nighttime.
Getting bright natural light during the day, particularly earlier in the day, helps reinforce that signal.
Meanwhile, excessive bright artificial light at night can send the opposite message.
In this episode, we talk about how modern life has almost completely flipped our natural light environment:
We spend our days indoors under relatively weak artificial lighting and then expose ourselves to bright LED and blue light at night.
That can interfere with the normal light-dark cycle that helps regulate sleep.
Is Blue Light Bad for You?
Blue light itself is not inherently bad.
Timing matters.
Natural daylight contains blue wavelengths, and bright daytime light helps promote wakefulness.
The problem is that modern artificial lighting can expose us to large amounts of blue-enriched light late into the evening, exactly when our biological systems are expecting darkness.
We discuss why reducing bright artificial light at night while increasing natural daylight exposure may better support circadian rhythm and sleep quality.
What Is Red Light Therapy?
Red light therapy, also called photobiomodulation, uses red and near-infrared wavelengths of light.
These wavelengths are being studied for their effects on cellular energy production, mitochondrial function, inflammation, tissue recovery and skin health.
Unlike UVB, conventional red light therapy does not produce vitamin D.
That distinction is important.
Red and near-infrared light and UVB light have very different biological effects.
What Does Infrared Light Do?
Infrared light is one of the largest components of natural sunlight.
It is also the wavelength responsible for much of the warmth you feel when standing outside in the sun.
In this episode, we discuss the relationship between infrared light and mitochondria, as well as why red and near-infrared therapy has become increasingly popular for:
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Skin health
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Cellular energy
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Mitochondrial support
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Exercise recovery
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Inflammation
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Muscle and joint recovery
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Metabolic health
Can Red Light Therapy Help Your Skin?
Red and near-infrared light are commonly used for skin rejuvenation and photobiomodulation.
Guti explains why he believes distance, wavelength, coverage and light intensity matter when choosing between a red light therapy mask and a red light therapy panel.
We also talk about the use of amber light alongside red and near-infrared wavelengths for skin and photodamage.
Can a UVB Lamp Help Produce Vitamin D?
Certain UVB lamps are designed to stimulate vitamin D production in the skin.
Guti created the MitoLux Sun Lamp to combine targeted UVB with red and near-infrared wavelengths.
Unlike a standard red light panel, the MitoLux includes a UVB mode specifically designed to stimulate vitamin D production.
We discuss how the device uses different programs based on the Fitzpatrick skin type scale, why UV exposure needs to be carefully dosed and why distance from the device matters.
Because UVB can cause burns and skin damage when used incorrectly, UV devices should always be used according to manufacturer directions.
MitoLux vs. a Standard Red Light Therapy Panel
One of the major differences is UVB.
A conventional red light therapy device usually contains red and near-infrared wavelengths.
The MitoLux includes both:
Red and near-infrared light for photobiomodulation
and
UVB light designed to stimulate vitamin D production.
Guti also explains why he designed the device to provide infrared light around the UVB exposure rather than delivering isolated UVB alone.
How Often Should You Use Red Light Therapy?
In the episode, Guti recommends using the red light or "healing" setting consistently rather than sporadically.
For the MitoLux specifically, he discusses approximately 10-minute red light sessions several times per week and explains that the UVB setting requires its own separate protocol based on skin type and distance.
Always follow the instructions for your specific device, particularly when UV wavelengths are involved.
Sunlight, Seasonal Affective Disorder and Winter Mood
For many people, winter doesn't just mean colder temperatures.
It means dramatically less light.
We discuss seasonal affective disorder, winter depression, morning light exposure and light therapy, along with the difference between a traditional 10,000-lux SAD lamp and red or UVB-based devices.
Traditional SAD lamps primarily work through bright visible light entering the eyes.
UVB and red light devices work through very different biological mechanisms.
In This Episode You'll Learn:
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Why modern indoor living may dramatically reduce natural light exposure
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The difference between UVA, UVB, visible and infrared light
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Why UVB is required for vitamin D production in the skin
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Why sunlight and vitamin D supplements are not necessarily biologically identical
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How the angle of the sun changes the wavelengths reaching your body
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Why people in Canada and northern climates may receive very little UVB during winter
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How morning sunlight supports circadian rhythm
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How artificial blue light at night may affect sleep
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The relationship between sunlight, hormones and testosterone
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Why infrared light is important for mitochondria
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How red light therapy works
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The difference between red light therapy and UVB therapy
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How red light therapy may support skin health and recovery
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How UVB lamps can stimulate vitamin D production
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How the Fitzpatrick skin scale is used when dosing UVB
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Why proper distance and exposure time matter with UV devices
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How MitoLux combines red, near-infrared and UVB light
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Why light exposure may become an increasingly important conversation in hormone health and longevity
Get 10% Off the MitoLux UVB Vitamin D Red Light Box
If you live somewhere that makes natural UVB exposure difficult during part of the year, you can learn more about the MitoLux UVB Vitamin D Red Light Box.
Use coupon code KM10 to save 10%.
Watch or Listen to the Full Episode
Watch the full conversation with Gerardo "Guti" Gutierrez on YouTube:
Or listen on Apple Podcasts and your favorite podcast platform.
Important: Sun exposure and UVB exposure are not risk-free. Excessive UV exposure can contribute to sunburn, premature skin aging and skin cancer. This episode discusses Guti's research, experiences and perspectives and is intended for educational purposes, not individualized medical advice.