Watch the news or talk to health influencers, and you’ll hear skyrocketing disease rates blamed on ultraviolet (UV) light.
The sun naturally emits large quantities of UV.
Modern medicine sometimes uses UVA and UVB light therapy to treat certain conditions.
So, is it a toxin or a key to the proliferation of human (or any form of) life?
In this article, I’m going to share the science of ultraviolet light. We’ll explore the benefits of UVA vs UVB, as well as how to use UV light therapy safely.
Unlike artificial indoor lighting, natural sun exposure includes red and infrared light, reducing UV toxicity
UVB triggers biologically superior vitamin D production, more effective than supplements, supporting immune function, bone health, and testosterone
Red and near-infrared light help minimize skin damage and optimize UV therapy results
Multiple studies show no increased risk of skin cancer with responsible UVB exposure, even long-term
Understanding Ultraviolet (UV) Light
The sun naturally emits a dynamic ratio of UVA, UVB, and UVC. It constantly changes throughout the day.
In the right dose, each has an important role. Before we explore the benefits of UVB phototherapy, it’ll help to understand the basic differences between the light wavelengths.
What is UVA (Ultraviolet A) light?
UVA (315-400nm) light has the longest UV wavelength (closest to visible light spectrum) and makes up about 95% of the sun’s UV rays that reach Earth’s surface.
A lot of the scientific research uses a subset called UVA1 which spans 340-400nm.
It penetrates deeper into the skin, and excess exposure contributes to wrinkles, premature aging, and skin cancer. UVA is unaffected by cloud cover or glass windows.
Tanning beds mostly emit UVA which triggers the production of skin-darkening melanin.
What is UVB (Ultraviolet B) light?
UVB (280-315nm) light mostly gets absorbed by the ozone layer, with only about 5% of UVB rays reaching Earth’s surface.
Excess UVB causes sunburn, and unlike UVA, these rays do not penetrate through glass Share on XUVB intensity depends on all kinds of factors, like geographical location, time of day, and season.
UVB light therapy is sometimes used medically, and is key to the production of vitamin D among many other important bodily substances which we’ll discuss shortly.
What is UVC (Ultraviolet C) light?
UVC (100-280nm) light has the shortest wavelength and is almost entirely absorbed by the ozone layer. It’s also the most damaging form of UV.
UVC is often used to sterilize, as it’s excellent at killing bacteria and viruses.
If humans get exposed to UVC, it can cause severe burns to the skin and eyes. We’re going to ignore UVC today, since it’s therapeutic application to health is virtually zero.
What is full-spectrum light?
Full-spectrum light (100-900nm) spans from UV, through visible light, and ends on the other end at infrared.
This is what the sun emits, and it’s something that manmade lights very rarely replicate.
This synergy of all wavelengths generally creates balance and protects against potential damage.
For example, exposure to red and infrared light before ultraviolet light can help protect the skin and minimize the harmful effects of moderate UV exposure.
Learn more in this honest review of the Solshine full-spectrum lamp.
Benefits of UVA, UVB, & Full-Spectrum Light Therapy
Natural sunlight includes a balance of UVA, UVB, visible light, and infrared—giving you true full-spectrum exposure.
The ratio of each component changes dynamically throughout the day.
| Spectrum | Penetration Depth 🧬 | Primary Benefits📈 | Safety 🩹 | Overexposure Dangers ⚠️ |
|---|---|---|---|---|
| UVA (315-400nm) | Deep (reaches dermis) | Boosts nitric oxide, may enhance mood, collagen stimulation (in moderation) | Generally safer than UVB but can still cause long-term skin damage | Oxidative stress, aging effects, potential DNA damage |
| UVB (280-315nm) | Shallow (epidermis) | Triggers vitamin D production, may support immune function | Requires careful dosing; can cause burns quickly | Burns, DNA damage, increased skin cancer risk |
| Full-Spectrum | Varies (combination of UVA & UVB) | Combines benefits of both UVA & UVB; balanced exposure for therapy | Requires precise control to avoid risks | Increased risk of burns, aging effects, and potential skin cancer |
If you can get outside for morning, afternoon, and evening light exposure, you’ll likely get enough of each.
If you’re unable to bask in mid-day sun, however, you may want to incorporate either UVA or UVB light therapy.
An interesting 2018 paper had the following to say about UV therapy,
“Thus, UV touches the brain and central neuroendocrine system to reset body homeostasis. This invites multiple therapeutic applications of UV radiation, for example, in the management of autoimmune and mood disorders, addiction, and obesity.”
How UV Light Touches the Brain and Endocrine System Through Skin, and Why
UVA benefits
UVA penetrates a few millimeters into the body where it increases the release of vasodilating nitric oxide into the bloodstream.
UVA also stimulates keratinocytes (skin cells) to produce Proopiomelanocortin (POMC), which results in increased levels of α-MSH (Melanocyte-Stimulating Hormone) and mood-boosting β-endorphins.
UVA stimulates the generation of reactive oxygen species (ROS), which cause oxidative stress but also signal repair mechanisms.
Here’s a short list of the benefits of responsible UVA light exposure:
- Blood flow & circulation
- Skin health
- Collagen stimulation
- Pain management
- Nitric oxide production
- β-endorphin production
- Circadian rhythm regulation
- Mood enhancement
- Appetite regulation
- Melatonin production
- Thyroid hormone production
- Gut microbiome (diversity and abundance)
- Immune system modulation
- Long-lasting tanning
- Skin melanin production
People often think of UVA light as harmful, but that’s not entirely true. UVA has important functions. Of course, all this assumes the appropriate dose of UVA.
While both UVA and UVB darken skin pigmentation, UVA is the spectrum responsible for the longer-term tan Share on XEven so, UVA seems to be much less beneficial compared to optimizing UVB light exposure.
UVB benefits
UVB does much of what UVA does, only stronger. Such as triggering the production of neuropeptides like α-MSH, β-endorphin, and ACTH.
It also has unique effects that UVA cannot replicate. Including, stimulating the production of activated (’sulfated’) vitamin D—and a whole lot more.
This ‘activated’ vitamin D is considerably more biologically useful than the unsulfated form present in all supplements.
Unlike the supplemental form, vitamin D produced through sun exposure protects the skin against DNA damage and disease Share on XThe increased levels of opioid chemicals like β-endorphin indicate that our biology is hardwired to reward us for spending time in UVB-rich light (i.e. sunlight).
Some of the many benefits of healthy UVB light exposure include improved [R, R, R, R]:
- Vitamin D production
- Nitric oxide production
- Blood flow and pressure
- β-endorphin production
- Bone health
- Immune regulation
- Pain management
- Appetite regulation
- Anti-inflammatory
- Mood improvement
- Energy level boost
- Melanin production
- Testosterone production
- Gut microbiome (diversity and abundance)
- Leptin hormone sensitivity
- Weight loss
- Skin rejuvenation (collagen, elastin)
- Anti-microbial (anti-viral, anti-fungal, anti-bacterial, anti-mold)
Melanin, a molecule produced from exposure to UV light and subsequent alpha-MSH activation has vast biological importance.
Melanin uniquely absorbs the full electromagnetic spectrum and acts as both as an energy storing battery and biological semiconductor.
This makes melanin one of the most important molecules in human biology.
This newer 2021 study came to some interesting conclusions,
“In humans, solar exposure enhances romantic passion in both genders and aggressiveness in men, as seen in analysis of individual questionaries, and positively correlates with testosterone level.”
Skin exposure to UVB light induces a skin-brain-gonad axis and sexual behavior
Clearly, UVB light is key to human health.
How to Safely Use UVA, UVB, & Full-Spectrum Light Therapy
UV radiation is often seen as the harmful part of sunlight, giving the sun an undeserved bad reputation.
Sunlight balances UVA and UVB rays with protective red and infrared wavelengths, helping the body naturally regulate its exposure.
Some research suggests that artificial UV therapy can be safe when used carefully. It should always be used in conjunction with a broad or full spectrum of red and infrared light.
UVA therapy is FDA-approved to treat some skin conditions [R]. Limited research suggests it is both effective at reducing pathogens and safe when used responsibly. [R].
Narrower wavelengths like “UVA1” seem to be better tolerated [R].
A 2023 study titled The realistic positioning of UVA1 phototherapy after 25 years of clinical experience and the availability of new biologics and small molecules: a retrospective clinical study mentioned that UVA1 therapy remains a valuable option [R]. The study stated:
“The present RWE retrospective study demonstrated that UVA1 phototherapy is an effective and safe treatment option for various skin conditions.”
Should you choose UVA therapy, I’d use small doses.
UVB therapy, on the other hand, has decent research:
- 2020 study involving 60,321 participants found that those undergoing UVB treatment had the same skin cancer risk as the control group [R]
- 2020 study of 100 patients found no melanoma or non-melanoma skin cancer in the group receiving narrow-band UVB therapy [R]
- 2019 study of 173 patients showed that narrowband UVB therapy is a safe and effective option for treating specific skin conditions and had no severe side effects [R]
- 2018 study of 22,891 psoriasis patients found that even long-term narrowband UVB phototherapy did not increase incidences of skin cancers [R]
- 2008 examination of 3,400 participants across 11 studies found that only one UVA study showed an increased rate of (genital) tumors [R]
Then, this 2022 study concluded:
“NB-UVB is a safe treatment method with few adverse effects as well as no increase in risk of any form of skin cancer seen in the literature.”
An update and review of narrowband ultraviolet B phototherapy for vitiligo
Interestingly, a study combining UVA with UVB found reduced skin inflammation and local blood flow peaks, suggesting reduced skin damage from the combo compared to UVB alone [R].
Another 2021 meta-analysis concluded similarly [R].
My recommendation?
Increase your photoprotection by consuming a diet rich in antioxidants (berries), carotenoids, pigments (like phycocyanin in micro-algae), melanin-rich mushrooms, methylene blue, shilajit, and astaxanthin.
I would strongly advise individuals with light sensitivities or certain skin conditions to consult a dermatologist.
So, if you’re wondering… which is better, UVA vs UVB therapy? It’s UVB, but both are helpful.
The Safe & Beneficial Way to Use UV Light Therapy
Exposure to natural UVA and UVB light is a major reason to bask in the sun.
Modern indoor lighting excludes these spectrums entirely due to concerns about their potential cancer-causing effects.
Savvy inventors have noticed how sunlight’s spectrum (visible, infrared, and UV) changes dynamically. Some now design lights that mimic the sun for better, healthier lighting.
This includes intelligently pre-exposing your body to protective red and near-infrared light before UV exposure. Then, applying specific frequencies after UVA and UVB exposure helps your body and skin repair efficiently.
When it comes to UVA vs UVB light therapy, science favors UVB. It’s more powerful, has more benefits, and is well-researched. It works even better when paired with UVA Share on XWhat about you? Do you use ultraviolet light therapy? Drop a comment below and let me know your thoughts.
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