LED Lighting (350-650nm) Undermines Human Visual Performance Unless Supplemented by Wider Spectra (400-1500nm+) Like Daylight
January 26th, 2026Via: Scientific Reports:
Life evolved under broad spectrum sunlight, from ultraviolet to infrared (300–2500 nm). This spectrally balanced light sculpted life’s physiology and metabolism. But modern lighting has recently become dominated by restricted spectrum light emitting diodes (350–650 nm LEDs). Absence of longer wavelengths in LEDs and their short wavelength dominance impacts physiology, undermining normal mitochondrial respiration that regulates metabolism, disease and ageing. Mitochondria are light sensitive. The 420–450 nm dominant in LEDs suppresses respiration while deep red/infrared (670–900 nm) increases respiration in aging and some diseases including in blood sugar regulation. Here we supplement LED light with broad spectrum lighting (400–1500 nm+) for 2 weeks and test colour contrast sensitivity. We show significant improvement in this metric that last for 2 months after the supplemental lighting is removed. Mitochondria communicate across the body with systemic impacts following regional light exposure. This likely involves shifting patterns of serum cytokine expression, raising the possibility of wider negative impacts of LEDs on human health particularly, in the elderly or in the clinical environment where individuals are debilitated. Changing the lighting in these environments could be a highly economic route to improved public health.
Light is so integral to our biology/health. Does it seem likely that the truncated frequencies and pulsed nature of LED lighting is going to be healthful?:
Grok: “LEDs are often driven with pulsing in two main ways, and the pulse frequencies vary depending on the type and application:AC-powered household/commercial LED bulbs and fixtures (without dimming)
These typically rectify AC mains power (50/60 Hz), resulting in light output that pulses at twice the line frequency: 100 Hz in regions with 50 Hz mains (e.g., Europe, much of Asia/Australia).
120 Hz in regions with 60 Hz mains (e.g., North America).
This is a very common source of flicker in standard LED bulbs, and it’s often imperceptible to most people but can cause issues for sensitive individuals or in video recording.
PWM dimming / pulsing for brightness control (common in LED strips, smart bulbs, automotive lights, displays, and dimmable fixtures)
Pulse-width modulation (PWM) rapidly switches the LED on and off to simulate dimming. The pulse frequency (how fast it cycles) typically falls in these ranges: Low-end / cheaper controllers: 100–500 Hz (can cause visible flicker or strobing, especially with motion).
Typical / standard range for acceptable performance: 1 kHz – 5 kHz (often 1–2 kHz; reduces visible flicker for most uses).
High-frequency / flicker-free designs (recommended for sensitive people, video/photography, or critical applications): 5 kHz – 30 kHz+ (20–25 kHz or higher is considered effectively invisible and safe for nearly everyone; some go up to 50–100 kHz or more).
Anything below ~1 kHz risks perceptible flicker or health effects (eye strain, headaches) for sensitive users, while above ~3–5 kHz it’s usually imperceptible.
In summary, the relevant pulse frequencies for LED lights are mostly in the 100 Hz to tens of kHz range, with 100–120 Hz being common for non-dimmable bulbs and higher values (kHz range) for dimmed or controlled LEDs. If you’re experiencing flicker sensitivity or using them for video, look for “flicker-free” or high-frequency PWM (>10–20 kHz) options. Let me know if you have a specific type of LED (e.g., bulbs, strips, car lights) in mind!”
6 months ago I was exploring with Grok whether humans may emit biophotons in the UVB frequency range–but none of the following research came up at the time. Apparently, it had already started to gain a bit of traction in 2024:
Me: I read somewhere of a bit of confirmation of my speculation that humans may produce vitamin D via the emission of biophotons in the UVB spectrum–can you bring up any recent support for that?
Searching the web
18 results
Grok: “Your speculation touches on an emerging hypothesis in biohacking and mitochondrial research circles, where internal biophotons—ultra-weak light emissions from biological processes, particularly in mitochondria—might include UVB wavelengths capable of triggering vitamin D synthesis from cholesterol precursors like 7-dehydrocholesterol, independent of sunlight. This is a niche idea, not yet mainstream in vitamin D biology (which overwhelmingly focuses on cutaneous UVB exposure from the sun), but it has gained traction recently through interpretations of new studies on cold exposure and metabolic activity. I’ll break down the key recent support below, drawing from scientific papers, expert discussions, and reviews published or discussed in 2024-2025.The Core HypothesisBiophotons are real phenomena: living cells emit extremely faint photons (on the order of 10-100 photons per second per square centimeter) as byproducts of oxidative metabolism and reactive oxygen species (ROS) reactions in mitochondria.
sciencedirect.com
These emissions span a broad spectrum, including visible light, near-infrared, and potentially ultraviolet ranges (UVA, UVB, and even traces of UVC).
youtube.com +1
The speculation is that during heightened mitochondrial activity (e.g., from cold exposure activating brown adipose tissue, or BAT), some biophotons in the UVB range (around 290-320 nm) could photolyze cholesterol in fat cells to form previtamin D3, mimicking solar UVB’s role in skin.
seagertp.substack.com +1
This internal process might help maintain vitamin D levels in low-sunlight conditions, like winter.Traditional vitamin D synthesis requires external UVB to convert 7-dehydrocholesterol in the skin to previtamin D3, which then isomerizes to vitamin D3.
pmc.ncbi.nlm.nih.gov +1
The biophoton idea extends this intracellularly, but evidence is indirect—biophoton intensity is ultra-weak, so skeptics question if it’s sufficient for meaningful synthesis. However, proponents argue that localized emissions in high-cholesterol environments like BAT could accumulate effects.Recent Support from Studies and Discussions2025 Polish Cryotherapy Study on Multiple Sclerosis Patients:A key piece of recent evidence comes from a study published in the Journal of Clinical Medicine titled “Whole-Body Cryotherapy Affects Blood Vitamin D Levels in People with Multiple Sclerosis” (Ptaszek et al., 2025).
seagertp.substack.com +2
Researchers exposed 15 women with MS to 20 sessions of whole-body cryotherapy (extreme cold, -110°C to -160°C for 1.5-3 minutes) over 4 weeks. They observed a statistically significant ~34% increase in serum 25-hydroxyvitamin D (the main circulating form) from a median of 34.97 ng/mL to 46.82 ng/mL (p=0.013). No such increase occurred in healthy controls or untreated MS groups.
The study didn’t directly measure biophotons or attribute the rise to them, but it noted the effect was specific to MS patients (who often have mitochondrial dysfunction and lower baseline vitamin D). This has fueled speculation: cold activates BAT mitochondria, boosting ROS and biophoton production, including UVB-like emissions that could drive vitamin D synthesis in adipose tissue.
ricciflow.substack.com
The authors suggested metabolic shifts in MS might amplify this, but didn’t explore mechanisms deeply.
Expert Interpretations and Mitochondrial Biophoton Research (2024-2025):In a 2024 podcast and video discussion, mitochondrial expert Dr. Alexis Cowan explained how cold-induced thermogenesis in BAT ramps up mitochondrial electron transport, generating biophotons in UV ranges (including UVB and UVC).
youtube.com
She links this to potential internal vitamin D production, noting it’s a way the body might compensate for low sunlight. Cowan cites biophoton measurements showing UV emissions during oxidative stress, which aligns with BAT activity.
Thomas P. Seager (engineer and biohacker) published articles and videos in 2024-2025 proposing that cold thermogenesis produces UVB biophotons in BAT, converting cholesterol to previtamin D.
seagertp.substack.com +2
He directly ties this to the Polish study, arguing it’s the first clinical evidence supporting biophoton-mediated vitamin D synthesis. Seager estimates that biophotons could provide “winter vitamin D” without sun, based on mitochondrial photon yield models.
A 2025 review on biophotons in aging (published in a biophysics journal) discusses UV emissions from cells, including how they interact with biomolecules like steroids (e.g., cholesterol precursors).
researchgate.net
It doesn’t explicitly mention vitamin D but notes UV biophotons can induce photochemical changes in nucleic acids and vitamins, providing a mechanistic plausibility.
Broader Context and Limitations:A 2024 bioRxiv preprint on UVB modeling for vitamin D synthesis across skin types reinforces that UVB (296-300 nm optimal) is key, but focuses on solar exposure.
biorxiv.org
No mention of internal sources, highlighting that the biophoton idea is still speculative.
Community discussions on platforms like Instagram and Substack (2024-2025) amplify this, with biohackers testing cold plunges and reporting anecdotal vitamin D boosts.
instagram.com +1
One post speculates biophotons might even raise testosterone via similar pathways.
Caveats: Biophoton UVB output is minuscule compared to sunlight (ultra-weak, not enough for tanning or burns), so effects might be subtle or tissue-specific. No direct in vivo measurements confirm UVB biophotons synthesizing vitamin D in humans yet—most evidence is correlative from cold studies. More research (e.g., isotopic tracing of vitamin D origins) is needed.
If this piques your interest, the Polish study is a good starting point for empirical support, and following researchers like Cowan or Seager could yield updates. If you have more details on where you read the original speculation, I can dig deeper.”