Circadian rhythms, non-native EMF and leptins

A very concise review as a starter piece

Dr. Jack Kruse knows a lot about circadian bodies, non-native EMF and leptins. He’s a neurosurgeon. He speaks a lot of truths on sunlight medicine in this podcast with Danny Jones. Please do watch this either before or after reading this starter piece.

One of things that turns my stomach about how we are all living these days is how the system that we are in is a construct of very, very bad ideas constructed by agents who are investing in making humans commodities. Whether the commoditization is in the context of in vivo or in silico “needs”, it is evident that we are part of a system that is incentivized to profit and cares not about the health of its commodities. Now this may sound “a bit much”, but all one has to do is look around to see the truth of these things absolutely everywhere.

Here’s an easy way to see this: think back to the 80s and now think about now and write down 3 things that are absolutely different, or more precisely, write down three things that didn’t exist back then that do now. Here are mine:

1. More dangerous chemicals in food, air and water

2. Non-native electromagnetic frequency-emitting devices in ubiquity

3. Indoor sedentary lifestyle where these indoor settings are very far removed from anything that might be considered natural - light-wise, sound-wise and air-wise

Circadian rhythms, non-native electromagnetic frequency (nnEMF) and leptins

Circadian rhythms drive sleep cycles, hormone regulation, and other biological processes in nearly all living organisms, including cyanobacteria. These rhythms are governed by internal circadian clocks, which synchronize these processes with the external environment. Light and temperature are key regulators of these clocks, fine-tuning them to the 24-hour day-night cycle.

Light-requiring organisms, such as plants, algae, and cyanobacteria, depend on natural light, not just for energy (via photosynthesis, which produces oxygen), but also to regulate their circadian clocks. These clocks orchestrate processes like growth, gas exchange, and even DNA repair, syncing them to the daily light-dark cycle. For example, cyanobacteria—the oldest known oxygen-producers—use their circadian rhythms to time photosynthesis during the day and nitrogen fixation at night, avoiding oxygen’s interference with the latter. Natural light acts as the primary cue, or zeitgeber, to reset and fine-tune these clocks daily.

Extending this to oxygen-breathing organisms like us: while we don’t need light for oxygen directly, our circadian clocks still hinge on light to regulate sleep, metabolism, and hormone release—like melatonin, which dims when morning light hits. Without natural light, our clocks drift, and studies show this de-sync can tank health, from sleep disorders to metabolic issues.

Light-requiring beings rely on natural light to keep their circadian clocks ticking right. It’s a deep evolutionary thread: light doesn’t just fuel life; it times it.

The human circadian rhythm is governed by a master clock in the suprachiasmatic nucleus (SCN), a cluster of about 20,000 neurons in the hypothalamus. The SCN synchronizes rhythms across the body, using light signals from the eyes to regulate melatonin production in the pineal gland—rising in darkness to trigger sleepiness, falling with light to wake us up. It also adjusts body temperature and other processes to align with the day-night cycle. In the schematic below, you can the location of the SCN and in case you’re wondering about those ridiculous COVID brain swabs being able to access/damage the SCN, it wouldn’t be possible since it’s protected by bone.

Figure 1: https://en.wikipedia.org/wiki/Suprachiasmatic_nucleus#/media/File:Suprachiasmatic_Nucleus.jpg

Beyond the SCN, peripheral clocks in organs like the liver, pancreas, lungs, and skin fine-tune local functions, such as metabolism or immune activity. These clocks sync with the SCN through hormonal and neural cues, creating a cohesive rhythm network, with natural light as the primary reset signal.

Disruptions—like jet lag, shift work, genetic mutations, neurological diseases, or nighttime screen light—can misalign the SCN and peripheral clocks. This leads to poor sleep, mood disorders, and higher risks of obesity, diabetes, heart disease, and cancer, all tied to the loss of natural light’s guiding role.

Figure 2: https://en.wikipedia.org/wiki/Circadian_rhythm#/media/File:Biological_clock_human.svg

Maintaining a healthy circadian rhythm relies on consistent sleep and light exposure patterns, ideally anchored by natural daylight. It’s a system evolved for sunlight’s cues—mess with it, and the body pays the price.

Natural light versus nnEMF

Natural light, primarily sunlight, is a full-spectrum electromagnetic radiation source that drives circadian rhythms, syncing the body’s master clock in the SCN with the 24-hour day-night cycle. It delivers a balanced mix of wavelengths—visible light, plus small amounts of UV and infrared—evolved to support life, boosting mood, vitamin D production, and sleep regulation. NnEMF, like those from artificial lights, screens, and wireless devices, differ sharply: they’re narrow-spectrum (often heavy on blue light) or radiofrequency-based, lacking the broad, natural profile. While natural light strengthens circadian alignment, nnEMF—especially at night—disrupts it, suppressing melatonin and throwing off sleep and hormonal balance. Both influence biology, but natural light nurtures where nnEMF often disturbs. The following diagram shows the span from 0 Hz (direct current) to 10²¹ Hz (gamma rays), divided into non-ionizing and ionizing radiation. where various frequencies and their applications are labelled: power lines (60-100 Hz), AM radio (520-1610 kHz), mobile phones (1.9-2.2 GHz), and Wi-Fi (2.4-5.8 GHz).

Figure 3: https://www.cancer.gov/about-cancer/causes-prevention/risk/radiation/electromagnetic-fields-fact-sheet

NnEMFs primarily lie in the non-ionizing part of the spectrum, spanning extremely low frequency (ELF, 10¹-10² Hz) through radio waves (10⁵-10⁹ Hz) and into microwaves (10⁹-10¹¹ Hz). Think power lines Wi-Fi and microwave ovens. Artificial sources differ from native EMFs like sunlight, which peaks in visible light (around 10¹⁵ Hz) with a broad spectrum including infrared and UV.

In terms of wavelengths, natural sunlight spans a wide range: ultraviolet (UV) from about 100-400 nanometers (nm), visible light from 400-700 nm, and infrared (IR) from 700 nm to over 1 millimeter, with peak intensity around 500-570 nm (green-yellow). This spectrum shifts throughout the day—bluer (shorter wavelengths, ~450-480 nm) in the morning to stimulate alertness, redder (longer wavelengths, ~620-750 nm) at sunset to wind down. This is why it’s important to get exposure to sunlight at different times during the day.

The SCN’s melanopsin-containing cells are especially sensitive to blue light (morning) around 480 nm, making it a key circadian signal. In contrast, nnEMF from LEDs and screens peaks heavily in the blue range (400-500 nm), often at 450-470 nm, with little to no red or IR, mimicking midday sun even at night. Wireless devices emit radiofrequency nnEMF (300 MHz to 300 GHz), wavelengths in centimeters to millimeters, far outside the visible spectrum and irrelevant to circadian photoreceptors, though some studies suggest they may still stress cells indirectly.¹²³ Natural light’s broad, dynamic range supports biology; nnEMF’s narrow, static output confuses it.

Leptins/Leptin Melanocortin Pathway

Leptins are hormones produced by fat cells (adipocytes) that regulate energy balance by signaling satiety to the brain, reducing appetite, and influencing metabolism. Discovered in 1994, leptin levels rise with fat stores, helping maintain body weight homeostasis. The leptin-melanocortin pathway is a key system in this process: leptin binds to receptors in the hypothalamus, particularly in the arcuate nucleus, activating pro-opiomelanocortin (POMC) neurons. These neurons release melanocortin peptides, like α-MSH, which stimulate downstream melanocortin-4 receptors (MC4R) to suppress appetite and boost energy expenditure, while inhibiting hunger-promoting AgRP neurons. Disruptions in this pathway, like leptin resistance, can lead to obesity and metabolic disorders.⁴⁵⁶⁷⁸

Figure 4: Schematic illustration: Pro-opiomelanocortin (POMC) neurons in the NTS have a more restricted set of projections. Both sets of neurons appear able to receive neural and endocrine signals from the body. https://pubmed.ncbi.nlm.nih.gov/33684608/

Metabolic disorders seem to be a recurring theme here and considering that cancer is simply a metabolic disorder, I think this warrants further investigation.

Leptin plays a critical role in the brain by acting as a key regulator of energy balance and appetite, primarily through its influence on the hypothalamus via the leptin-melanocortin pathway. Produced by fat cells (P.S. not only is leptin produced by fat cells, but fat cells are immunologically-active), leptin circulates in the blood and crosses the blood-brain barrier to bind to receptors in the arcuate nucleus of the hypothalamus, signaling the body’s energy stores. This triggers the leptin-melanocortin pathway: leptin activates pro-opiomelanocortin (POMC) neurons, which release α-melanocyte-stimulating hormone (α-MSH) to stimulate melanocortin-4 receptors (MC4R) in downstream brain regions like the paraventricular nucleus. This suppresses appetite and increases energy expenditure.

Simultaneously, leptin inhibits agouti-related peptide (AgRP) neurons, which otherwise promote hunger. This dual action fine-tunes feeding behavior and metabolism, linking fat reserves to brain-driven decisions. Disruptions - such as leptin resistance, seen in obesity - can impair this pathway, leading to overeating and metabolic disorders, underscoring its importance for maintaining brain-body homeostasis.

So all in all, leptin is really important in regulating metabolism. When the leptin-melanocortin pathway system falters, as is the case with leptin resistance, it can lead to metabolic dysfunction, including weight gain and conditions like type 2 diabetes.

This all ties back to natural light.

Leptin and the leptin-melanocortin pathway are intricately tied to natural light for proper maintenance because circadian rhythms, driven by light exposure, regulate their function. As already described, natural light synchronizes the SCN (the brain’s master clock), which influences hypothalamic regions like the arcuate nucleus⁹ where leptin acts. This ensures leptin production and sensitivity peak during optimal times—typically daytime—aligning with feeding and activity patterns, while melatonin, boosted by darkness, fine-tunes leptin’s rhythm. The leptin-melanocortin pathway, which suppresses appetite via POMC neurons and MC4R signaling, relies on this timing: studies show disrupted light exposure (e.g., artificial light at night) desynchronizes the SCN, impairing leptin signaling, reducing receptor sensitivity, and leading to overeating or metabolic issues. Thus, natural light’s full-spectrum, time-specific cues are essential for maintaining the pathway’s role in energy balance. Are you getting the picture?

As a point of interest from the above-cited article entitled: “Arcuate Nucleus of the Hypothalamus: Anatomy, Physiology, and Diseases”:

The arcuate nucleus of hypothalamus (ARH) consists of neuroendocrine neurons and centrally-projecting neurons. The ARH is the center where the homeostasis of nutrition/metabolism and reproduction are maintained. As such, dysfunction of the ARH can lead to disorders of nutrition/metabolism and reproduction.

So this is also about reproduction folks.¹⁰ THM: leptin is really important and leptin-resistance (when your brain doesn’t respond to leptin)¹¹¹² is likely a very prolific and serious problem in humans at this point in time.

To maintain healthy leptin levels using natural light sources will align your circadian rhythm with the day-night cycle to support optimal leptin production and sensitivity. As many of you have already likely heard, a good way to start your day is with exposure to morning sunlight—ideally 20-30 minutes of full-spectrum light (rich in blue wavelengths around 480 nm)—to signal the SCN and boost alertness, which enhances leptin’s ability to regulate appetite via the leptin-melanocortin pathway. Throughout the day, maximize time outdoors or near natural light to reinforce this rhythm, as consistent light exposure helps synchronize the hypothalamic arcuate nucleus, where leptin acts to curb hunger. In the evening, minimize exposure to artificial light, especially blue-heavy nnEMF from screens, and allow exposure to dim, warm light (mimicking sunset’s redder wavelengths, 620-750 nm) to promote melatonin production, which supports leptin’s nighttime rhythm. A consistent sleep schedule, anchored by these natural light patterns, further prevents circadian disruptions that can lead to leptin resistance, ensuring the hormone effectively maintains energy balance and metabolism.

One last thing on dopamine: the reward chemical messenger. Dopamine is a neurotransmitter that makes you feel good by influencing motivation and reward and indeed, interacts with leptin and circadian rhythms under natural light’s influence. When the SCN is activated to regulate leptin, dopamine production is also given a boost which means you feel better and eat better because it’s tied to leptin’s satiety signals via none other than the leptin-melanocortin pathway! So dopamine’s reward system aligns with leptin’s appetite suppression when timed by natural light’s blue-rich morning spectrum. So you might have already guessed that disruptions in natural light cycles can suppress dopamine release and impair leptin sensitivity. Unfortunately, those dopamine hits are likely sought out by clicking and scrolling and over-eating.

Bottom line: Go get some sun. Early morning walks are excellent. Leave your shoes behind (ground). Leave the phone behind. Read a book in the evening. Sleep luxuriously. Eat when you’re hungry. Enjoy a better life. :)

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