Light and Health

In The Electric Body, I wrote about the fact that we are electrical beings, that the body runs on electrical signaling at every level, from the nervous system to the heart to cellular communication. That article was about the current running through you. This one is about the energy coming in from outside.

Light is electromagnetic radiation. It sits on the same spectrum as the radio waves, microwaves, and EMFs we covered in the EMF article, just at different frequencies. The difference is that visible and near-visible light isn’t some artificial addition to our environment. It’s the original electromagnetic input. The one our biology was built around.

And we’ve quietly removed most of it from our daily lives.

Light Is Not a Utility

We treat light like a switch. Flip it on, the room is bright, you can see. That’s the extent of most people’s relationship with it.

But the body doesn’t just see light, it absorbs it, responds to it, and uses it as a biological input at nearly every level. Light sets your circadian rhythm. It triggers hormone production. It drives cellular energy. It synthesizes vitamin D. It releases nitric oxide. It regulates your mood, your sleep, your immune function, and your metabolism.

When you change the light environment, you change all of those things. And we’ve changed the light environment dramatically.

Where Light Sits on the Spectrum

The sun delivers three bands of light that matter most for health, all at once, in a ratio that shifts naturally throughout the day:

• Infrared (below visible), you feel it as heat. It penetrates tissue and drives cellular energy production. The morning sun is heavy in infrared before the UV rises.
• Visible light, regulates circadian rhythm, mood, alertness, and hormone production. Brightness matters more than most people realize.
• Ultraviolet (above visible), responsible for vitamin D synthesis and immune function. Also the part that burns if you overdo it.

No artificial light source replicates this combination. Not LEDs, not fluorescents, not full-spectrum bulbs. The sun is the reference standard, and everything else is a rough approximation.

What Sunlight Actually Does in the Body

This isn’t an exhaustive list, but it gives a sense of scope:

• Vitamin D synthesis, UVB light on the skin triggers vitamin D production. It’s not really a vitamin, it functions more like a hormone and influences hundreds of biological processes. Deficiency is linked to weakened immunity, bone loss, depression, cardiovascular disease, and increased cancer risk. Deficiency is also extremely common.
• Circadian rhythm, Light hitting the retina sets the master clock in the brain (the suprachiasmatic nucleus), which coordinates sleep, hormone release, body temperature, digestion, and immune function. Morning light is the primary input.
• Melatonin, Produced at night in the absence of light, but the daytime light exposure is what calibrates the cycle. A weak daytime signal means weak nighttime melatonin production. This is why people who stay indoors all day often sleep poorly.
• Cortisol, Morning light triggers the cortisol awakening response, setting the body’s energy curve for the day. Without it, you wake up groggy and your energy never quite peaks.
• Serotonin, Precursor to melatonin, produced in response to bright light. Low light environments correlate with low serotonin, this is the mechanism behind seasonal affective disorder.
• Nitric oxide, UV exposure releases nitric oxide stored in the skin, which lowers blood pressure and improves cardiovascular function. This is one reason outdoor populations tend to have better cardiovascular health.
• Mitochondrial energy production, Near-infrared light penetrates tissue and interacts with cytochrome c oxidase in the mitochondria, improving ATP production. This is the mechanism behind red light and near-infrared therapy, it’s not mystical, it’s photobiology.

How We Broke the Light Environment

For all of human history, light meant the sun during the day and fire or darkness at night. A clear, consistent signal that the body could calibrate around. Then Edison changed everything, and suddenly we could extend the day indefinitely. Within a few generations, most people shifted to spending 90% or more of their time indoors under artificial light.

The problem isn’t that artificial light exists. The problem is that it’s nothing like sunlight, and we act as if it is.

The spectrum problem, LEDs and fluorescent lights produce a narrow, spiky spectrum heavily weighted toward blue light, missing most of the red, infrared, and UV that the sun provides. Your biology doesn’t know what to do with a signal that’s all blue and no red.

The intensity problem, A bright office is 300-500 lux. An overcast day outside is 10,000-25,000 lux. Direct sunlight is over 100,000 lux. We think we’re in bright rooms when we’re actually in dim caves by biological standards. The circadian system needs intensity to calibrate properly, and indoor lighting doesn’t come close.

The timing problem, Blue-heavy screens and LED lighting at night tells the brain it’s still daytime, suppressing melatonin production and delaying sleep onset. We’ve essentially disconnected the off switch.

And then there’s the cultural layer: we demonized the sun. “Avoid sun exposure, wear sunscreen always” became public health doctrine. The actual risk is burning, intermittent, excessive exposure. Not moderate, regular exposure, which is associated with better health outcomes across multiple studies.

The Sunscreen Question

This one gets people’s attention, so it’s worth being direct about.

The conventional advice is to wear sunscreen every day, avoid direct sun, and cover up. The nuance that gets lost is that chronic moderate sun exposure is associated with better health outcomes, while it’s intermittent burning that correlates with skin cancer risk. These are not the same thing.

Chemical sunscreens absorb into the bloodstream, the FDA has confirmed this, and many contain endocrine-disrupting compounds. Mineral sunscreens (zinc oxide, titanium dioxide) physically block UV without absorption and are a better option when you actually need sun protection.

The more practical approach: build a base gradually. Know your skin type. Use clothing and shade strategically. Use mineral sunscreen for extended exposure when burning is a real risk. Don’t fear the sun, fear the burn.

Meanwhile, vitamin D deficiency is widespread and linked to a long list of chronic diseases. The “avoid the sun” message has its own health costs that rarely make it into the conversation.

Red Light and Near-Infrared Therapy

Red (600-700nm) and near-infrared (700-1100nm) light penetrate skin and tissue. The primary mechanism is interaction with cytochrome c oxidase in the mitochondria, improving ATP production and reducing oxidative stress. This is established photobiology, not fringe science.

It’s used clinically for wound healing, joint pain, skin conditions, and muscle recovery. Consumer devices, panels, masks, handheld units, have made it accessible outside clinical settings. The evidence base is growing, and the mechanisms are well understood.

It’s not a replacement for sunlight. The sun delivers the full spectrum, and no device replicates that. But as a supplement, especially in winter, for people who work indoors, or for targeted recovery, it’s worth knowing about.

One thing worth noting: the morning sun delivers red and infrared light naturally. The first light of the day is heavy in these frequencies before UV rises later in the morning. This is one reason morning sunlight feels different than midday sun, and one reason it’s so effective at setting the circadian clock without any burn risk.

The Master Clock

The circadian system isn’t just about sleep. It coordinates nearly every biological process on a roughly 24-hour cycle, hormone release, immune function, body temperature, digestion, cell repair, cognitive performance. Sleep is just the most visible output.

Light is the primary zeitgeber, the “time-giver”, that synchronizes the whole system. Morning light exposure is the single most important input. It sets the cortisol curve, primes serotonin production, and calibrates the melatonin release window for that night. Get the morning signal right, and a lot of downstream processes fall into place.

Disrupted circadian rhythm is linked to obesity, diabetes, cardiovascular disease, depression, weakened immunity, and increased cancer risk. Shift workers have measurably worse health outcomes across the board, this is the cost of chronic circadian disruption. It’s not just about feeling tired. It’s a systemic problem.

Light as Medicine Isn’t New

We talk about light therapy like it’s a modern discovery, but sunlight was used medicinally long before we understood the mechanisms.

Egyptian, Greek, and Ayurvedic healers all incorporated light into treatment. Dr. Auguste Rollier ran Swiss Alpine clinics in the early 1900s treating tuberculosis with structured sun exposure, and had documented success. Florence Nightingale insisted patient wards receive direct sunlight. Dr. Niels Finsen won the Nobel Prize in 1903 for treating lupus vulgaris with concentrated light.

It’s worth noting that many of these traditions didn’t draw a clean line between light as medicine and light as something more fundamental. Across cultures and centuries, light shows up as a metaphor for consciousness itself, the divine light, the light of awareness, the white light reported in near-death experiences. Whether that’s poetic language or pointing at something deeper is its own question, but it’s interesting that the cultures who took light most seriously as a healing tool also tended to treat it as the most basic element of reality.

This entire medicinal tradition was largely abandoned when antibiotics and pharmaceuticals arrived, not because it didn’t work, but because sunlight can’t be patented. That doesn’t mean the biology changed. It means the economics did.

Getting Your Light Right

If you take one thing from this article, make it the morning. Get outside within the first hour of waking, even 10-15 minutes, even on a cloudy day. Outdoor overcast light is still dramatically brighter than anything indoors. It resets the circadian system, triggers the cortisol awakening response, and sets up the entire hormonal cascade for the day.

Beyond that:

• Spend more time outside during the day. Lunch breaks, walks, working near windows. The intensity matters.
• Evening light hygiene. Dim the lights after sunset. Use warm-toned bulbs. Limit screen brightness and use night mode or blue light filters. The goal is to stop telling your brain it’s noon at 10pm.
• Consider red/NIR therapy as a supplement, especially in darker months or if you spend most of your day indoors.
• Rethink the sunscreen reflex. Build gradual exposure. Use mineral sunscreen when you need it. Don’t fear moderate sun.

The single biggest change for most people is morning outdoor light. It’s free, it takes 10 minutes, and it recalibrates a system that’s been running on bad data.

The Throughline

This is the fourth piece in a series that started with The Electric Body, the idea that we are electrical beings operating in an electromagnetic environment. Grounding covered reconnecting with the earth’s electrical charge. EMF Fields and Health covered the artificial electromagnetic environment we’ve built around ourselves.

Light is the natural electromagnetic input we evolved with. It’s energy, not metaphorically, literally. Photons hitting your skin and your retina drive real biological processes that affect how you sleep, how you feel, how you heal, and how well your body functions at every level.

And there’s a curious thing at the edge of all this. Physics tells us that light is the speed limit of the universe, the constant everything else is measured against. Mystics across every tradition describe enlightenment in terms of light, not darkness, not sound, not heat. Near-death accounts converge on the same image. Whether that’s coincidence, metaphor, or a hint about the nature of the thing, I don’t know. But the more you learn about what light actually does in the body, the less strange the old language sounds.

We optimized our chemistry with food and supplements. We optimized our mechanics with exercise and movement. The light environment is the one most people haven’t thought about yet, and it might be the easiest one to fix.