Podcast Blog Login

Breaking Down the Effects of Sunlight Frequencies on the Human Body

 

Sunlight is far more than just a source of warmth and illumination - it’s a natural powerhouse of frequencies that interact not only with plants, but with our bodies in profound ways.

From ultraviolet (UV) rays to infrared (IR) and visible light - the rainbow, each wavelength offers unique benefits that support physical and mental well-being.

Let’s dive into the remarkable ways the sun’s spectrum enhances our health, exploring the science behind the most researched spectra: UV-A, UV-B, Infrared (IR), Red light, and Blue light.

 

Ultraviolet-A:

UV-A (315–400 nm) sets in roughly about an hour after sunrise. UV-A penetrates deeper into the skin than UV-B that comes in later, and offers its own set of benefits, particularly for circulation and immunity:

 

  1. Dopamine Release
    All sunlight, including UV-A, influences dopamine production in the brain. This "feel-good" neurotransmitter enhances mood, motivation, and focus. 
  2. Nitric Oxide & Blood Pressure Regulation
    UV-A triggers the release of nitric oxide in the skin, a molecule that dilates blood vessels, improves blood flow, and lowers blood pressure naturally.
  3. Immune Regulation & Reduced Autoimmunity
    UV-A modulates immune responses, potentially reducing overactivity that leads to autoimmune conditions.

  

Ultraviolet-B:

UV-B rays, found in the 280–315 nanometer range, are often celebrated for their role in vitamin D synthesis, but their benefits extend far beyond that. Here’s how UV-B works its magic:

 

  1. Vitamin D Production
    When UV-B rays hit your skin, they trigger the conversion of cholesterol in the skin into previtamin D3, which becomes vitamin D3. This essential nutrient supports bone health, immune function,  mood regulation and more.
  2. Testosterone Boost
    UV-B exposure has been linked to increased testosterone levels in men. Studies suggest that UV-B stimulates the hypothalamic-pituitary-gonadal axis, enhancing hormone production and vitality.
  3. Melanin Synthesis
    UV-B stimulates melanocytes in the skin to produce melanin, the pigment responsible for tanning. Beyond aesthetics, melanin acts as a natural shield against UV damage and potentially as a source of energy for the mitochondria.
  4. β-Endorphins: Nature’s Painkillers
    UV-B exposure triggers the release of β-endorphins, opioid-like compounds that elevate mood and reduce pain perception, explaining the euphoric "sun high." Beyond endorphins, UV-B may directly reduce pain by modulating inflammation and nerve sensitivity, offering a natural analgesic effect.
  5. Leptin Sensitivity & Fat Loss
    UV-B helps regulate leptin, the hormone that signals fullness. Improved sensitivity may curb overeating and support metabolic health. By enhancing leptin sensitivity and boosting metabolism via vitamin D, UV-B can indirectly aid weight management efforts.
  6. Anti-Viral & Anti-Bacterial Properties
    UV-B has germicidal effects, damaging the DNA of viruses and bacteria on the skin and in the air, bolstering your body’s defenses.
  7. Gamma-MSH: Salt Balance & Blood Pressure
    UV-B stimulates gamma-melanocyte-stimulating hormone (γ-MSH), which regulates sodium balance and, in turn, helps maintain healthy blood pressure.
  8. Alpha-MSH: Immune Regulation
    Alpha-MSH, another UV-B-induced peptide, supports immune balance.

 

IR-A (Infrared-A):  

Infrared-A (700–1400 nm) penetrates even deeper, reaching subcutaneous tissues and delivering cellular-level benefits:

 1. Subcellular Melatonin Production

IR-A stimulates mitochondria to produce melatonin locally, a potent antioxidant that protects cells from oxidative stress.

2. Photoprevention vs. Sunburn

IR-A preconditions skin against UV damage, reducing sunburn risk by enhancing cellular resilience. That’s why it’s important to start your day by exposing your skin to sunrise.

3. Builds EZ Water
IR-A helps structure water in cells into "exclusion zone" (EZ) water, a gel-like state that supports cellular hydration and function.

4. Anti-Inflammatory Effects
By reducing oxidative stress and cytokine activity, IR-A calms inflammation throughout the body.

5. Builds Collagen
IR-A stimulates fibroblasts to produce collagen, promoting skin elasticity and wound healing.

6. Nitric Oxide & Blood Pressure Regulation
Like UV-A, IR-A boosts nitric oxide, enhancing circulation and cardiovascular health.

 

Red Light:

Red light (620–750 nm), part of the visible spectrum, targets mitochondria for systemic benefits:

1. Mitochondrial Function
Red light enhances cytochrome c oxidase activity in mitochondria, boosting ATP production and cellular energy.

2. Reduces Blood Clotting
By improving blood flow and reducing platelet aggregation, red light supports a healthier circulatory system.

 

Blue Light: The Circadian Setter

Blue light (450–495 nm) is most abundant in the sky during midday when the sun is high, particularly on clear days. This is due to Rayleigh scattering, which scatters shorter wavelengths like blue (400–500 nm) more effectively than longer ones.

Peak abundance occurs around noon to early afternoon when sunlight travels through less atmosphere, maximizing scattering of blue light. Overcast skies or times near sunrise/sunset reduce blue light, as longer wavelengths (reds/oranges) dominate. Here’s what it does:

1. Circadian Health 
Blue light signals the suprachiasmatic nucleus in the brain to suppress melatonin and align your sleep-wake cycle, promoting alertness, when you go out into the morning sunlight.

2. Serotonin Production
Morning blue light boosts serotonin, enhancing mood and emotional resilience throughout the day.

3. Adipose Regulation
Melanopsin is the blue light photoreceptor located in our eyes, skin and subcutaneous fat. It works together with leptin. Through that couple, blue light influences fat cells, promoting fat breakdown and aiding metabolic balance.

 

So after this quick breakdown, if you've been paying attention, you may be wondering: if UV-B is so potent, what about people living in areas where UV-B is absent a huge chunk of the year? What about UV-A’s effects on POMC - the so important Proopiomelanocortin pathway that regulates mood, stress response, metabolism, tanning, immune function, cardiovascular function, and more?

Well, the truth is that UV-A (315–400 nm) does exert an effect on POMC, but it’s less direct and weaker compared to UV-B’s starring role.

While UV-B is the primary driver of POMC expression in the skin, UV-A contributes in a supporting capacity, influencing the POMC gene through different mechanisms and with subtler outcomes.

 

Let’s break it down:

UV-B’s effect on POMC is straightforward - it hits the skin, activates DNA damage pathways (like p53), and ramps up POMC transcription in keratinocytes and melanocytes fast and hard.

UV-A, with its longer wavelength, penetrates deeper into the dermis but doesn’t trigger that same acute DNA damage response. Instead, it works more through oxidative stress and secondary signaling.

Studies peg UV-A’s impact on POMC as modest—maybe 20–30% of UV-B’s potency under similar doses, per experiments like those in Photodermatology, Photoimmunology & Photomedicine (2005).

So people who live at higher latitudes - where UV-B levels drop significantly, especially in winter, face a real challenge when it comes to POMC activation and its downstream benefits.

With the sun low on the horizon and UV-B often blocked by the atmosphere (or absent entirely during polar nights), our ancestors had to adapt through diet, lifestyle, and biology to stay healthy. Here’s how they used to manage without that steady UVB-POMC boost: 

1. Dietary Workarounds

  •  Vitamin D from Food: UVB’s biggest POMC perk is vitamin D production, which drives peptides like α-MSH and β-endorphins. At high latitudes, people historically leaned on fatty fish (salmon, mackerel, cod liver), seal blubber, and other marine sources rich in preformed vitamin D3. For example, Inuit populations in the Arctic thrived on diets delivering 10,000 IU or more daily, bypassing the need for UV-B synthesis.

 

2. Evolutionary Adaptations

  •  Lighter Skin: Populations at higher latitudes, like Northern Europeans, evolved lighter skin over millennia to maximize UV-B absorption when it’s available (e.g., summer months). Less melanin means even weak UV-B rays can trigger POMC and vitamin D production, giving them an edge over darker-skinned ancestors in sunnier climates.
  •  POMC Sensitivity: Some research hints that northern-adapted groups might have genetic tweaks enhancing POMC expression or peptide efficiency, though this is speculative and less studied. It’s a possible compensatory mechanism for lower UV-B doses.

 

3. More UV-A Year Round

  •  UVA and Visible Light: While UVA’s effect on POMC is weaker, it still contributes via oxidative stress and nitric oxide, as we discussed. High-latitude folks get more UV-A year-round (it’s less filtered by the atmosphere), which might nudge POMC enough to sustain low-level peptide activity.

 

4. Lifestyle Adjustments

  •  Outdoor Time in Summer: When UV-B is available (spring to fall), high-latitude people historically maximized exposure - fishing, herding, or farming. This “stockpiling” of vitamin D and POMC peptides in fat tissue could tide them over leaner months, though stores deplete after 2 - 3 months without replenishment.

 

  •  Cold Adaptation: POMC peptides like ACTH tie into stress and energy regulation. Cold climates might upregulate these via non-UV pathways (e.g., stress hormones), partially offsetting UV-B’s absence. Nature has a back-up system for the lack of sunshine at higher latitudes and that's through cold exposure.

 

5. Cultural and Physiological Resilience

  •  Mood and Endorphins: Without UV-B-driven β-endorphins, northerners leaned on physical activity (saunas, skiing) and social bonds to boost natural opioids. Seasonal affective disorder shows the limit of this, though—low POMC activity in winter hits mood hard for some.
  •  Immune Trade-Offs: α-MSH from POMC helps immunity, but high-latitude diets (rich in omega-3s) and cold-induced immune priming (e.g., via mild hypothermia) might fill the gap. Still, vitamin D deficiency leaved them vulnerable, historically seen in higher rickets rates before supplementation.

 

The Reality Check

Our ancestors at high latitudes survived, not thrived, in winter UV-B droughts. They made do with fish, fair skin, and grit, but it’s a compromise.

Now folks, get out there and get some sun, wherever you are!