Sugar Supercharges Red Light Therapy: Effectiveness for Diabetics vs Athletes

Could sugar be the underappreciated key component to Photobiomodulation effectiveness? If we could understand the role of glucose with Red Light Therapy, we may be able to optimize treatments, reduce variability, and answer common questions about how the therapy is working. 

We covered in a previous article the supplements and topicals that have been clinically studied with Photobiomodulation (the science of Red/NIR Light Therapy). The point being that Light can provide cellular energy, but the essential building blocks still come from proper diet and nutrition. 

However, the most profound dietary influence on Red Light Therapy that has been right under our noses this whole time - sugar. 

Red/NIR Light Therapy upregulates the mitochondria to produce more ATP - Adenosine TriPhosphate. ATP is the chemical energy currency that is credited with powering 90% of cellular functions in animal cells. [3]

But we often forget the classic biochemistry as to how ATP is typically formed, from the breaking down of sugars and carbohydrates into glucose from our food. [4]

"Glucose metabolism is the core process by which cells obtain energy, providing adenosine triphosphate and metabolic intermediates through glycolysis and the tricarboxylic acid cycle and supporting cell proliferation, migration, and functional maintenance." [5]

Thus, when the mitochondria increases ATP production from Red Light Therapy, then it needs to pull in more glucose to consume for that process. As explained by the following quote from a PBM study:

"However, to increase mitochondrial metabolism after PBMT, an increase in Krebs cycle (citric acid cycle) activity is necessary. "

...

"In this context, blood glucose plays a relevant role in the response to PBMT, as it is the primary substrate for glycolysis in the cell's cytosol to generation of pyruvate and then to induce Krebs cycle activity." [6]

This was demonstrated in the famous blood glucose experiment by Professor Glen Jeffery. Healthy humans (non-diabetic) were treated with Red Light Therapy and then given a sugar drink, and it was shown that the blood sugar spike was reduced by about 7.5%. [7]

We must remember that the blood sugar reduction was not a spontaneous occurrence. The participants had to do a "glucose challenge test" to chug 75 grams of sugar water in 2 minutes, which is 290 calories of glucose. [7] This crucial step is often overlooked when this study is shared online. 

Infographic that describes PMID: 38378043 [7]

In other words, we may not have observed a significant response without the large influx of sugar. So, we could say that sugar was an essential component for the success of this study.  

This was not the first time there was observations of Red Light Therapy's effects on glucose regulation. And leads us to consider if sugar is playing a pivotal role in Photobiomodulation mechanisms. 

Glucose is Essential for Photobiomodulation:

In commentary from a 2024 review article on Photobiomodulation for diabetes, it is clear that Red Light Therapy treatments on the muscles or blood reduces blood glucose. 

"The level of blood glucose can be directly decreased, and various glucose metabolic pathways in the body can be mobilized through PBM (Photobiomodulation) irradiation of skeletal muscle or blood." [8]

In fact, one 2023 study confirms that glucose is essential to Photobiomodulation's effects. The absence of glucose leads to no effects. As indicated by this quote:

"In summary, we found that the benefits of photobiomodulation, in particular in changing ATP and ROS levels, were induced only when there was glucose available." [9]

A 2024 editorial article aptly titled "Does photobiomodulation require glucose to work effectively?" summarizes several studies that show there is no effect by PBM when glucose is absent. 

One profound quote is:

"We hypothesize that photobiomodulation is most effective in stimulating mitochondrial function when there is glucose readily available for use (Figure 1B and C). The glucose may be available directly from the circulation or from glycogen stores in muscle, liver, or within the astrocytes in the brain (see above)." [10]

Studies on isolated cells cultured in higher glucose mediums often show more activity under PBM than normal glucose levels. Or, in some cases the function of cells in high glucose mediums is restored back to normal levels. [11][12][13][14]

One 2015 study showed that injecting Pyruvate in conjunction with Low Level Light (LLL) also enhanced the effects. Pyruvate is an intermediate molecule formed during glucose metabolism, so it makes sense that this would also directly enhance Photobiomodulation effects. 

"Notably, the effect of LLL on cell survival was stronger in the presence of pyruvate than in the presence of glucose or lactate (Figure 4B). These data suggest that LLL and energy metabolic modulators together could maximize ATP production and cell survival under a condition of hypoxia." [15]

This opens up much more therapeutic potential of using exogenous glucose, pyruvate, or other metabolic enhancements for Red Light Therapy. 

A New Biphasic Dose Response Mechanism:

Conventionally, we assumed the Biphasic Dose Response was due to excess concentrations of the Outputs of mitochondrial metabolism; for example the excess ATP, NO, ROS, and Ca+ will trigger cellular inhibition. 

However, this new perspective makes us question if an inadequate supply of glucose may also be another reason for observing a lack of response from Red Light Therapy. Thus, may be an alternative manifestation of what we call the Biphasic Dose Response. 

Perhaps it is the availability of glucose that plays a large role in what we believed to be the Biphasic Dose Response. Low availability of glucose leads to a blunted response, and adequate levels of glucose leads to the optimal response. This will be yet another variable to juggle when considering dosing. 

Interindividual Response Variability:

It is well know that humans have a widely variable response to Photobiomodulation treatments. This is also a common issue in exercise science. It has been given a name below called Interindividual Response Variability:

"The different responses of humans to an apparently equivalent stimulus are called interindividual response variability." [16]

If a large group of people are given the same exercise protocol, there will be a widely variable response. Given the same "dose" of red light therapy, there is a widely variable response in different people. There are variable responses to standardized exposures to pharmaceutical drugs, supplements, other medical devices, diets, stress, etc.

Generally, we only hear the headline from a study as the average result. But that does not mean all of the people in the study got the same benefit. Some may have been non-responders, and some as hyper-responders. Averaging just causes the reported data summary to meet in the middle. 

Averaging the data hides the individual variability. Worse, gold-standard science of Randomized Controlled Trials (RCTs) apply a standardized dosing protocol to all participants, when better results could have been gotten by adjusting the doses to accommodate for bio-individuality.  

"Today, individualized drug dosing is underutilized, as modern medicine routinely follows standard dosing established by randomized controlled trials, which are viewed as the gold standard for evidence-based medicine. There is an opportunity to greatly improve patient care with precision dosing as the health care system continues to evolve." [17]

The same phenomenon occurs in Red Light Therapy. Given the same "dose", there are widely variable responses in different individuals. We know that giving people the recommended dosing ranges and education on dosing variables will allow them to experiment with their dosing protocol to find what works best for themselves. 

Dr. Hamblin comments on this phenomenon in an interview:

"The thing that confuses people even more than you've just mentioned, is that different people respond differently. So, some individuals are highly sensitive to light, to red and near-infrared light. Some individuals, as I've said, are like blocks of wood, you can shine light on them all day and nothing will happen. And the majority are in-between, it is like a bell curve.

It is the hyper-sensitive individuals that will most often complain that they got adverse effects from Photobiomdulation. How do you know who these hyper sensitive individuals are?

And the answer is: Well, they are hyper sensitive, they complain about all sorts of things, you know, they are allergic, they don't like loud noises, they don't like bright light, they can only eat certain kinds of food, their whole life seems to be governed by being hyper-sensitive. So if you are going to treat these kinds of people with Photobiomdulation, be very careful. Because, they are the ones that complain about all sorts of things going wrong.

The majority people, as I've said, are in the middle. And it is difficult to overdose them on light. I'm not saying you can't do it. But, most, and it is not a sudden drop off. Most people can figure it out from trial and error."

-Dr. Hamblin, Interview [1]

So, we can generally predict the hyper-responders are those whom exhibit high sensitivities. They may be already sensitive to sunlight, EMFs, chemicals, foods, odors, noise, or other stimulus. 

But what about the non-responders? Are there any ways to identify them? Does that mean the non-responders are those that are healthy and resilient to most stimulus? 

The problem is that we see fit influencer giving their anecdotal recommendations for Red Light Therapy dosing (high intensities, overdosing, high heat) to a wider population filled with hyper-responders. These same fit influencers are often also resilient to stresses like EMF, Flicker, Blue light, and noisy fans - which is why they often have no qualms about promoting products with high levels of these potentially detrimental features. 

And it is estimated that 1-5% of the population that are hyper responders that are suffering when trying to follow healthy influencer's dosing recommendations. Especially since the recommendations are not evidence-based, but based on their own personal anecdotes. 

Perhaps we can use this glucose theory to help us better identify the non-responders, and avoid issues like this in the future. 

Summary of Practical Implications:

From this perspective, we can use this glucose theory of Photobiomodulation to explain many effects of Red Light Therapy. And more importantly, it may explain much of the inconsistent dosing and variability we see in the data and anecdotal reports. 

Aspects the Glucose Theory can Explain:

• Effectiveness of PBM on diabetes, diabetes complications, and other diseases related to impaired glucose metabolism. 
• A common symptom of many mitochondrial diseases have hallmarks of glucose disfunction, which is why PBM has the potential to treat them. 
• Inconsistent benefits for athletes or otherwise fit and physically active individuals.
• Variability in effectiveness based on time of day or meal timing that may affect blood sugar status around PBM treatments. Leading to differences in benefits.
• Side effects such as "detox" reactions or fatigue caused by PBM lowering blood sugar.
• The correlation between high-sugar diets and light exposure.
• Adding Sugar to some Photobiomdulation protocols may be the key to obtaining benefits in some non-responder groups. 

It seems that glucose availability is a key aspect of PBM effectiveness. Some treatments may be enhanced or optimized based on timing of meals, time of day, sugar intake, exercise, or baseline sugar status. 

In this blog we will examine two widely contrasting treatment groups under Photobiomodulation. 

1. Diabetics - with hallmarks of elevated glucose levels and impaired sugar metabolism.
2. Athletes - with characteristic lower glucose levels and improved sugar control. 

Under the theory of sugar's crucial role in Photobiomoduation, we should be able to see stark contrasts in these groups in how they respond to Red Light Therapy treatments. 

Diabetes: Mitochondrial Dysfunction or Impaired Glucose Metabolism?

The main marketing appeal of Red Light Therapy is the ability to improve mitochondrial function. However, mitochondrial dysfunction is often synonymous with impaired glucose metabolism.

We focus on the mitochondria because it is a marketable buzzword, but perhaps the real mechanism is the improvement in sugar metabolism. 

The best way to highlight this mechanism is in treatment of patients with diabetes. The hallmarks of diabetes are impaired glucose metabolism, insulin resistance, and metabolic dysfunction. Which, is also often distilled down into claiming that diabetes is a mitochondrial disease. 

Without a doubt, Photobiomodulation has shown great promise for managing blood sugar and insulin in diabetic patients. 

"The widespread demonstration of the role of PBM in regulating blood glucose is now well-established in the literature." [8]

Over the last few years there have been several comprehensive review articles on Photobiomodulation applications for diabetes management. These have highlighted the ability of PBM to alleviate nearly every symptom and complication that is also associated with diabetes. 

• Regulates blood sugar
• Improves insulin sensitivity
  
• Treats non-healing diabetic wounds and ulcers
• Manages diabetic retinopathy
• Improves diabetic peritonitis (gum issues)
• Mending diabetic neuropathy and reducing associated pain 
• Provides neuroprotection in diabetics
• Reduced depression and anxiety
• Improved overall quality of life, mobility, and autonomy

[8][18][19][20][21][22][23][24]

A study of whole body red light therapy on obese women showed these promising results on glucose metabolism:

"Emerging evidence suggests that PBM may favorably influence several physiological systems relevant to obesity and metabolic health, including muscle performance [10], glucose metabolism [11,12], inflammation [13,14], and vascular function [15]." [25]

It is clear that Photobiomodulation has profound and consistent effects for those individuals with impaired glucose metabolism. We have been blinded by the mitochondrial mechanisms and have not properly examined Red Light Therapy from the lens of sugar utilization. 

Glucose Metabolism in Medical Conditions:

It is clear that many diseases, deficiencies, and symptoms can be characterized by impaired glucose metabolism. Here are a few examples of conditions that can be treated with Photobiomodulation and the underlaying defect of glucose impairment. 

1. Wound Healing

As we know, accelerated wound healing is one of the most easily observable benefits from Photobiomodulation. It is no surprise that there is a glucose metabolism component to wound healing, as noted by the following article:

"In mammalian cells, glucose serves as the primary energy source, and its metabolism is essential for maintaining cell growth, survival, and various functional activities. Aberrations in glucose metabolism are not only closely associated with impaired wound healing but also linked to the pathogenesis of numerous diseases." [26]

2. Skincare and Wrinkle Reduction

Fibroblasts are the cells in the skin that produce collagen. Which are upregulated with Red Light Therapy as the mechanism for managing wrinkles. In addition, fibroblast function is crucial to build new cells to heal wounds. Of course, sugar metabolism is a key aspect of fibroblast function. 

"Fibroblasts are integral to sugar metabolism within the skin. Their ability to maintain stable sugar metabolism is essential for preventing the formation of advanced glycation end products (AGEs) [36]. AGEs are compounds that are formed when proteins, including collagen and elastin, become glycated due to the exposure to excess sugar. " [27]

3. Pain

Pain relief is a tremendous application for Red and Near Infrared light therapy. Even the mechanisms of pain can be traced to impaired glucose metabolism. As opposed to our classical thinking that it is derived from nerve signals and inflammation. 

"Abnormal glucose metabolism plays an important role in the occurrence and development of chronic pain. " [28]

"The incidence of abnormal glucose metabolism in patients with rheumatoid arthritis was considerably higher than the general population. " [29]

4. Hair Loss

Even hair growth requires proper glucose metabolism:

"These results suggest that glucose metabolism is required for expression of signature genes associated with hair induction." [30]

As well, there are many links between hair loss and poor glucose metabolism:

"Insulin resistance, metabolic syndrome, and obesity have been linked to hair loss, although controversy remains about the relationship between these conditions." [31]

Thus, Photobiomodulation may be targeting glucose metabolism in the scalp to improve hair growth. 

5. Retinal (eye) Diseases:

Diseases of the eyes often manifest in high glucose (hyperglycemia) conditions:

"This wide range of evidence implies that dietary hyperglycemia is etiologically related to human aging and diseases, including DR and AMD. In this context, these diseases can be considered as metabolic retinal diseases." [32]

6. Brain Diseases and Glucose Dysfunction

Alzheimer's Disease (AD) is often referred to as Type 3 Diabetes. As it also contains many of the characteristics of diabetes that presents itself in the brain. [33]

In general, most NeuroDegenerative Diseases (NDDs) can be connected to impaired glucose metabolism:

"In NDDs, metabolic imbalance driven by mitochondrial dysfunction becomes a central pathogenic feature. This metabolic imbalance exhibits early complex bidirectional interactions between glucose and lipid metabolism [49,50]. " [33]

Parkinson's Disease (PD) has also been strongly associated with impaired glucose metabolism:

"Glucose control is impaired in moderate to advanced non-diabetic PD patients" [34]

Photobiomodulation has been confirmed to improve glucose metabolism in the brain in several studies, as confirmed by the two quotes below:

"Among them, PBM regulates microglial polarization and inhibits neuronal apoptosis, which may be related to its regulation of mitochondrial energy metabolism, promotion of oxidative phosphorylation, and inhibition of glycolysis." [35]

"Taken together, the data support the hypothesis that transcranial laser photobiomodulation improves intracellular signaling pathways linked to cell survival, memory, and glucose metabolism in the brain of aged rats." [36]

It is easy to get caught up with buzzwords about mitochondrial function, inflammation, and the outputs of energy production like ATP. 

However, perhaps if we focus more on glucose metabolism, then that could illuminate a better understanding of mechanisms and treatment applications for Photobiomodulation.

Inconsistent Benefits for Fit, Active Individuals:

Red Light Therapy marketing often appeals to healthy and fit individuals that are trying to be proactive with their health, or gain an extra boon to their wellness routine. Implying that treatments on healthy people with PBM will "supercharge" their cells.

However, glucose levels and metabolism in healthy individuals are already in the normal range. PBM is good at bringing impaired cells back to normal. Not necessarily bringing normal cells up to supernatural function. 

Exercise itself already is well established in regulating glucose and improving mitochondrial function. Thus, the effects of Red Light Therapy in fit people that routinely exercise may be redundant. Especially if they can exercise outdoors in sunlight. 

This has been shown many times in Red Light Therapy studies on athletes. Effectiveness on athletes or with simultaneous physical activity has been inconsistent and many studies report no significant effects for athletic performance or recovery. 

[37][38][39][40][41][42]

As one 2025 study clearly notes in summary of published research on the full-body research on athletes:

"Whole-body PBM may improve sleep quality but shows no evidence of benefits for exercise recovery or performance." [43]

Professor Glen Jeffery comments on this phenomenon of treating athletes with Red Light Therapy in a recent interview: 

"We got absolutely nothing out of it. Absolutely nothing. The story that develops is: if you are super fit, you don't need it. You just don't need it."

...

"You don't need the big panel, you know, and stand in front of it for four weeks, where you are really super fit. You are wasting your time."

-Prof. Jeffery, Interview [2]

Glen Jeffery does acknowledge that athletes do get a meaningful effect from using Red Light Therapy after strenuous exercise.

"In terms of use for athletes, and similar sports people. What you really need to do is forget about it before you do anything, because your body is already in a very good position. You are super fit. You are not super fit when you are finished, your mitochondria are in a really rough time, they will take time to recover."

...

"Your recovery times are quicker in young healthy people, if they have an exposure to long wavelength light after heavy exercise. If you can get them in that situation, you are reducing the probability of tendon damage, in particular. Your recovery time certainly."

...

"Its stupid to take super-fit people, and asking them, 'can we make you fitter'? No. Stress them. It is all about stressing people. You cans stress them with age, you can stress them with disease"... "Or you can stress them with heavy exercise." 

-Prof. Jeffery, Interview [2]

Bringing this back to our theory for this blog. Heavy exercise can cause impaired glucose metabolism. Thus, the intervention of Photobiomodulation at a strategic time may help accelerate the recovery from exercise. 

"This reduction in mitochondrial activity coincided with affecting the body’s ability to metabolize glucose in the blood."[44]

...

"at a certain level of physical effort, there is stagnation and even a decrease in performance, simultaneously with the disruption of mitochondrial activity, which decreases drastically in strong workouts, aspects proven on muscle biopsies."[44]

According to a Photobiomdulation for sports review article quote above, restoring glucose metabolism after heavy exercise is a mechanism for the athletic benefits. 

Mitochondrial Function Limits - the Ceiling Effect:

The so-called "Biphasic Dose Response" hinges on the concept of hormesis. Cellular functions and metabolites are regulated into a physiological range. When below or above the ideal range, that is when cellular performance is hindered until it is restored to normal.

So, instead of supercharging the cells, we must consider that there is a maximum threshold of performance on the upper end of the range. Going beyond the range (super) would actually be a detrimental condition. 

A recent 2026 article combined Aerobic Exercise (AE) and PBM to improve heart health in mice. They found the exercise alone gave the best effect, and that PBM made no additional effect, and may have even slightly reduced the benefit. [45]

"In contrast, PBM failed to augment the benefits of AE. Several explanations may account for this finding: (1) a ceiling effect, whereby AE alone maximised physiological adaptations;" [45]

Their first proposed explanation is that the exercise alone provided a benefit up to a ceiling of benefits. Similar to how we discussed the plateau or switch effect of benefits in a previous blog. Once we reach 100% effect, there is no additional benefit to doing more. 

Our cells have a "ceiling" of energy production and function that is governed by hormesis. Thus, the ultra-fit and healthy cells may not have much margin to gain benefit from Photobiomodulation.  

According to Professor Jeffery:

"If you have got players at that level, if you can improve them by 1%, that is significant."

-Prof. Jeffery, Interview [2]

Ultra-fit people, athletes, and generally healthy people have a smaller margin in which Red Light Therapy can offer improvements. Unless they are competing against other high performers, a 1% improvement may not be noticeable in an otherwise fit person. 

One study showed that stressed cells have an anti-inflammatory effect from Photobiomodulation (PBM). But normal cells have an increase in inflammation and ROS from PBM. 

"It has been found that PBM can produce ROS in normal cells, but when used in oxidatively stressed cells or in animal models of disease, ROS levels are lowered." [46]

Usage of PBM for fit, healthy people must be much more strategic around heavy exercise, cellular stresses, injury, or other conditions. Since they already have healthy glucose metabolism in their cells, there is less margin for PBM to offer improvement. Thus, it must be employed as part of a long term recovery program, and not as an acute performance boost. 

Exercise Conflicts with Red Light Therapy 

The other theory of the mouse experiment was that Red Light Therapy conflicted with the ROS produced by exercise. Depending on the timing of the effect, Red Light Therapy could either double-dip on the ROS production, or blunt it by reducing ROS prematurely for the exercise recovery benefits. 

"Because aerobic exercise relies on transient increases in reactive oxygen species to activate endogenous antioxidant defenses, immediate post-exercise PBM application may have blunted this adaptive signaling cascade." [45]

A meta-analysis of RCTs also found that Photobiomodulation Therapy (PBMT) was mostly effective on physically inactive people. They showed there was no significant benefit for physically active people. 

So, during sedentary periods of time for an individual, Red Light Therapy can offer the most obvious benefits. However, there seems to be a conflict when using Red Light Therapy during periods of physical activity. 

One 2023 study found that when Photobiomodulation is combined with prolonged heavy exercise, the benefits become attenuated (diminished). 

"These results indicate that PBMT and previous high-intensity exercises might share the same mechanistic effects on faster oxidative metabolism. Thus, further studies are necessary to better elucidate the combined effects of different priming exercise intensities (e.g., warm-up) and PBMT on oxidative metabolism and endurance performance." [48]

This indicates that there is a shared mechanism between Photobiomodulation and Exercise. If that is the case, then they both may be stacking the effects to compete for the same biphasic dose response. 

The authors indicate the "oxidative metabolism" is a shared pathway. Which means they may be competing for glucose.

Thus, we may have a case where Exercise and PBM may be competing for the same Input of glucose, and may be double-dipping on the output of ROS. As studies and Prof Jeffery indicates, the timing of PBM and exercise is a key consideration. Some studies have proposed that PBM implemented around warmup periods may be optimal. [49][50]

Discussion 1: Exercise + Red Light Therapy + Sugar = Supercharged?

Individuals with high muscle mass generally have better baseline glucose regulation and lower postprandial (after-meal) glucose levels. Even without exercise. Thus, there is likely less margin for Red Light Therapy to improve glucose in that population. [51][52][53]

It has been well established that mild exercise after meals can help regulate blood sugar and reduce the postprandial glucose spike. A simple walk outside is recommended to manage blood sugar after meals, which we can now appreciate has the added benefit of sunlight exposure. [54][55][56]

In other words, we could postulate that Exercise can make Red Light Therapy redundant in these contexts. However, Red Light Therapy could be a good Exercise Mimetic for people whom are sedentary or somehow unable to exercise regularly.  

Heavy or prolonged exercise is often associated with hypoglycemia, a lowering of blood sugar below 70mg/dl. [57]

As we established earlier, Photobiomodulation can have a glucose-lowering effect. And may in some cases lead to hypoglycemia. [58][59]

Carbohydrate or glucose intake is often utilized to prevent hypoglycemia for athletes engaged in heavy or prolonged exercise. [60]

Discussion 2: Side Effects Explained by Glucose Drops

Some reported side effects to Red Light Therapy may be fatigue, brain fog, or headaches. Although rare, this is most often reported by new users of full-body Red Light Therapy. 

Reports of these side effects are met with explanations that it is a "detoxification" (detox) or "herxheimer" (herx) reaction. [61]

These terms are often used as a misnomer due to the lack of proper explanation. In some cases these can be true, for example PBM may mobilize toxins from the fat or modulate the immune system in response to bacteria, but so far the science has not provided an exact explanation. 

The simplest explanation may be that Photobiomodulation has made an unexpected swing to blood sugar levels.[58][59] The symptoms of some of these side effects often match the side effects of hypoglycemia (low blood sugar). [62]

These side effects usually only occur in newcomers to Red Light Therapy as the body adjusts to the new metabolic conditioning. It is often recommended to start slow and intake proper fluids and electrolytes. But we must now wonder if some sugar consumption may alleviate those initial side effects. 

Discussion 3: Diet and Lifestyle of Healthy Metabolism

There had been a trend over the past ten years for low-carbohydrate, ketogenic diets. The extreme example has been the carnivore diet, eating only meat.

However, in recent years we have seen many of the prominent figures like Dr. Mercola and Dr. Saladino of these low-carb diets start to change their stance and incorporate more sugar, carbohydrates, and fruits into their diet. 

Rather than simply adding in some more sugars into their diet like a normal person craving a dietary deficiency, these influencers had to make a thing out of it. So, they claim to adopt a more "Ray Peat" style diet to justify their shift with science. 

The late Dr. Ray Peat is famous for his "pro-metabolic" diet and lifestyle science education. When a person has a healthy metabolism and avoids metabolic detriments like polyunsaturated oils and blue light, then they can not only tolerate sugar, but sugar may be an essential part of a healthy metabolism when incorporated properly. 

These influencers often had a more natural lifestyle of appreciating outdoors, sunlight, and Red Light Therapy. Dr. Peat had been a proponent of incandescent red heat lamps. 

This is a roundabout introduction to the strong anecdotal connection to sunlight exposure, healthy metabolisms, and intake of sugar. We will now review some of the corroborating science. 

As one study notes, bright light in the morning (morning sunlight) may actually stimulate appetite:

"The physiological role of increased appetite, plasma glucose levels, and triglyceride levels due to bright light exposure in the morning may be to mobilize energy in order to prepare the body for physical activity." [63]

Another recent study notes that we may crave more sugar under higher temperatures (i.e. summertime). 

"added sugar consumption is positively related to temperature, notably within 12–30 °C at a rate of 0.70 g °C⁻¹. This is primarily driven by the higher consumption of sugar-sweetened beverages and frozen desserts." [64]

However, this additional sugar appetite craving is often balanced by an increase in metabolism. Which results in a stable energy balance. In other words, it does not cause weight gain due to the improved metabolism provided by the light. This was shown in experiments using Ultraviolet light on rodents. [65][66][67]

Thus, this preliminary overview shows a strong correlation between healthy light exposure, strong metabolisms, and dietary demands for sugar.

In other words, our correlation works in both directions. Sugar availability improves Photobiomdulation effects, and the effects of light can signal for more sugar (appetite). This is likely not a coincidence, since the body would be built to demand more energy when our metabolism is being boosted by sunlight. 

Discussion 4: Sunlight on Metabolism:

As always, we must remind the reader that sunlight can deliver most of these same benefits of improving glucose metabolism and managing diabetes. 

A recent 2026 article showed that more time spent by windows exposed to sunlight vastly improves glucose metabolism:

"Continuous glucose monitoring revealed that participants spent more time in the normal glucose range, and whole-body substrate metabolism shifted toward a greater reliance on fat oxidation during daylight." [68]

There has been shown to be an inverse relationship between sunlight exposure and Type 2 Diabetes. The more sunlight, generally the less diabetes. [69]

A study on children showed that glucose and insulin were improved in the summer and autumn. [70]

In young athletes it was shown that more sunlight is correlated to improved sleep. Which has important implications for recovery and performance. [71]

A study on elite soccer players showed that Sunlight and Vitamin D supplementation was able to improve testosterone and performance in the winter. [72]

So, we can see that many of the same benefits (or more) can be gotten with adequate sunlight exposure. 

Conclusions:

Photobiomodulation has become a popular method for supporting mitochondrial function.

Mitochondrial function has been connected to improved health, energy, and youthfulness. The decline of mitochondrial function can be connected to most modern chronic diseases, aging, and poor performance. Thus, health claims around mitochondria are not only a popular buzzword, but a workaround for making indirect medical claims. 

However, this fixation of vaguely "improving mitochondrial function" often masks the true mechanisms of Photobiomodulation. It leads us to believe that any cell can be supercharged with light, regardless of it's current function, condition, or environment.  

We noticed a pattern of Photobiomodulation having a strong effect on glucose consumption, utilization, and metabolism. The availability of glucose seems to have a important impact on the effectiveness of this therapy. The lack of glucose may hinder or blunt those expected benefits. 

We reviewed several studies that have directly confirmed that glucose is required for Photobiomdulation to work. Or, it was required to demonstrate a significant effect. 

And we reviewed two treatment groups with widely disparate glucose situations. Diabetics, which Photobiomodulation is confirmed to support nearly all aspects of the disease and it's complications. And athletes, which often shows inconsistent results and needs more strategic implementation to do properly. 

We proposed that an additional intervention of Sugar+Photobiomodulation may be the key to improving the effects of light for these difficult cases such as athletic performance. 

There is even an interesting connection that sunlight, bright light, and healthy metabolisms seem to crave sugar. A greater cellular demand for sugar should correspond to mechanisms that control appetite and consumption. 

Red Light Therapy may be a life-changing treatment to those with sedentary, indoor lifestyles that are unable to exercise regularly. However, like most drugs or therapy, it can be used as a temporary intervention until the person is healthy enough to go outside in sunlight and exercise. 

The margins and efficacy for healthy, fit, active people are more nuanced and complex. It may be implemented properly around recovery periods, injury, or with more consideration to timing. Meal timing, and time of day may also play a role in glucose availability. 

 

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