To access the Libraries please log in:

LightSensitiveLight sensitivity is a problem for many people with an autoimmune or inflammatory illness. Skin has the ability to convert natural light into vitamin D (the ‘sunshine vitamin’).

Patients who are chronically ill often report increased sensitivity to sunlight, heat and artificial light (especially fluorescent). They feel worse when exposed to light and instinctively avoid it.

We believe that if cells (keratinocytes) in the skin are infected with intracellular bacteria, the natural regulation of photosynthesis that limits the amount of vitamin which is produced, may be thwarted. Thus, solar energy may overstimulate cellular activity, resulting in an increase in cutaneous production of vitamin D3, 25-D and 1,25-D following sun exposure. Elevated 1,25-D often causes inflammatory symptoms.

Lehmann et al. found that skin (dermal fibroblasts and keratinocytes possess VDR) has the capacity to synthesize 1,25-D and represents an important target tissue for 1,25(OH)2D. Seasonal variations in 1,25-D have been observed at all levels of 25-D and sunlight exposure appears to have an influence on 1,25-D very similar to that of 25-D.

Feeling better in the sun

Some chronically ill patients feel worse in winter and better in the summer because increased light exposure elevates vitamin D levels which reduces the ability of the immune system to kill bacteria and bacterial killing causes herx symptoms.

This study found that "Exposure to ultraviolet light, especially UVB wavelengths, can impair immune responses in animals and humans."

This study found that in the summer, when vitamin D3 is highest, 1,25-D down-regulated the immune system.

See also:
Vitamin D Photosynthesis and Latitude
Vitamin D Photosynthesis, Clothing and Sunscreen
Vitamin D Photosynthesis, Pollution, Tall Buildings, Shade and Clouds
Vitamin D Photosynthesis and Skin Pigmentation

Avoiding sunlight

Patients should experiment to find the level of natural and artificial light they can tolerate without experiencing intolerable symptoms or elevating their 25-D to an immunosuppressive level. Only a few will need to limit their light exposure to 30 lux (this is about as dark as a dim restaurant) at all times. Most are able to tolerate varying degrees of light exposure which should be experienced during daytime hours only, to facilitate better quality of sleep. During recovery, it's recommended to cover most skin exposed to sunlight (long pants/shirt and hat are adequate) but in time, exposure to light becomes less of an issue.

Patients on Inflammation Therapy (IT) are not instructed to live in total darkness. This could disrupt the wake-sleep cycle (a circadian rhythm) and result in insomnia or cause them to become out of phase with other circadian or ultradian rhythms (e.g., metabolic, hormonal, CNS electrical, or neurotransmitter).


Sunlight includes ALL daylight (natural light) occurring between dawn and dusk. Even on a cloudy day or in the shade, even far from the equator or in a location known for its rainy days, patients can get too much radiation from natural light in just a few minutes of skin exposure.

Patients not previously sensitive to light often become light sensitive during IT. Symptoms that increase during or after exposure to light are evidence of light sensitivity.
Light sensitivity will vary from mild to extreme. Most patients who are ill enough for IT are, or will be, light sensitive and may need to stay indoors as much as possible during daylight hours (dawn to dusk) and cover up carefully when going outdoors and especially while driving to prevent the symptoms sun exposure causes.
Light sensitivity caused by sunlight falling on skin and artificial light falling on the eyes usually occurs only during the first 1-2 years of IT and diminishes gradually. The level of light exposure a patient can tolerate during IT can be determined with cautious experimentation and assessment. Some patients can get by with a little cheating on sun or artificial light exposure without feeling too bad. Others who cannot avoid light exposure cannot continue therapy because they become too symptomatic.
Symptoms due to light exposure can either occur within minutes or can take up to 3 days after exposure to either sunlight or bright lights, making assessment difficult unless light is avoided diligently for several days.
Light sensitivity symptoms can be similar to Herxheimer symptoms so it's important to eliminate light exposure as a cause while also adjusting medications to achieve tolerable symptoms.
Reducing light exposure (and to some extent limiting ingested vitamin D) before beginning Benicar can cause an increase in symptoms due to improved immune system function.
Eye protection
Most patients need to avoid natural light and bright lights falling on the eyes.

The effect of light falling on the eyes is thought to be due to stimulation of the amygdala with resulting psychological symptoms (depression, irritability, headache, nausea, etc.). Eyes adapt to the ambient light level (with pupil dilation) and some may need to protect from this stimulation in all environments. For some, exposure of their eyes to too much light can make the road to recovery very rocky due to increased symptoms. Everyone should test their limits and see what level of light exposure their eyes can accept.

We recommend that Benicar not be initiated until adequate sunglasses are obtained. See Sunglasses.

Bright lights (fluorescent in offices and stores, halogens, stage lights) and high intensity lighting (natural light in some stores or airports) may also increase symptoms so NoIRs plus a hat with a brim should be worn in those environments.

If sunglasses are needed for watching TV or computer, a good UV-blocking pair is adequate for this artificial light only. Computer brightness should be turned down to a level that is comfortable for the eyes. Darker backgrounds can make reading on the computer easier too.
Although infrared protection in sunglasses is only needed for natural light, it's difficult to find "regular" dark sunglasses that block out enough other light. There's a lot of blue spectrum light emitted from fluorescent lights, so it is important to use a dark amber colored lens for adequate protection indoors unless the lighting is incandescent and low (30 lux).
As recovery progresses, patients will need less eye protection. For example, when light sensitivity diminishes, the NoIR 10% will suffice for outside use and the lighter 40% can be used indoors.
Patients should wear the level of eye protection that allows adequate visibility, feels comfortable for your eyes (this should be evident initially) and that seems to be needed to keep symptoms tolerable (this may be evident as recovery progresses).

If you're having difficulty seeing with sunglasses in a particular situation, you may need a lower level of protection (e.g., 10% rather than 2%) or may be able to forgo sunglasses in that situation. Be sure that you can see adequately to maintain safety in all situations (e.g., driving).

Your need for eye protection may change (up, down or back again) as therapy progresses so it's important to be flexible.
Cardiac symptoms
For most patients, light sensitivity symptoms are merely unpleasant, resulting in neurological phenomena such as eye photosensitivity, headache and fatigue. But sun (natural light) exposure does have the potential to increase cardiac and respiratory Herx symptoms, and to influence lab tests. Avoidance of sunlight is particularly important for the Th1/Th17 patient with cardiac symptoms to prevent a sudden serious cardiac event.
Many patients, with apparently minor inflammatory symptoms, do not realize until they start IT that they are actually quite ill. Because it is impossible to know prior to therapy if someone has significant sub-clinical inflammation, it is wise to  be cautious with light exposure.
Sun exposure may increase inflammation everywhere and may not be perceived as light sensitivity but could be evident as any type of symptom, including worsening lab results.
Patients who linger outside or subject themselves to avoidable outings may sabotage their chance of success with IT if symptoms become intolerable.
The decision to begin IT if sunlight avoidance is not practical or desirable, should be considered carefully by the patient in consultation with his/her physician, after a careful physical assessment and a thorough discussion of the risks versus benefits.
Some patient may find it very difficult (mentally and/or physically) to make lifestyle adjustments that facilitate avoiding natural light to reduce symptoms. For some, these symptoms are the price they have to (or want to) pay for recovery.

Sunscreens (sun blocks)

Most sunscreens are insufficient to protect against the effect of significant sun exposure. The use of sunscreen may cause patients to become too complacent about avoiding sunlight exposure. For details, see Sunscreens.

"Effect of sunscreen on vitamin D synthesis; sunscreens are used to protect the skin from ultraviolet A (UVA) and UVB waveband exposure that is associated with deoxyribonucleic acid (DNA) damage—the same UVB exposure that is needed for vitamin D synthesis. Experimental studies suggest that sunscreens can decrease cutaneous vitamin D synthesis (Misra et al., 2008). However, emerging evidence suggests that although sunscreens are effective, many may not actually be blocking UVB because they are improperly or inadequately applied. Thus, sunscreen use may not actually diminish vitamin D synthesis in real world use, although further study is needed to verify its actual impact (Diehl and Chiu, 2010; Springbett et al., 2010)."
Dietary Reference Intakes for Calcium and Vitamin D (2011)Food and Nutrition Board (FNB)

Dawn and dusk
Patients who are extremely light sensitive are only safe in low light. The light level at dawn and dusk may be low enough to allow outdoor activities during that limited time.
The light spectrum

Beyond the visible spectrum of light, there is UV (ultraviolet) light at one end of the spectrum (the short, invisible electromagnetic wave lengths) and IR (infrared) light at the other end of the spectrum (which are longer, invisible electromagnetic wave lengths of light).

Infrared waves are light waves that are slightly longer than visible light waves. They're found to the right of visible light in the electromagnetic spectrum. Infrared rays create most of the heat from sunlight and incandescent light bulbs.

All of these wave lengths (incident radiation), both the visible wave lengths and the invisible UV and IR wave lengths, are called incident radiation.

The visible wave lengths and the invisible wave lengths may provide enough solar electromagnetic energy to cause the production of 1,25-D within skin cells by converting sterol precursors into 1,25-D, especially if the keratinocytes are infected by intracellular CWD bacteria.


Any radiation, even heat or diathermy, may increase symptoms.

Humans perceive infrared radiation as "heat radiation", which is one method of energy transport. This may be why many patients with chronic illness feel very uncomfortable when they become overheated. IR heat sources and getting very hot in general may adversely affect some people by possibly increasing some inflammations and cytokines to too high levels.

Some increase in inflammation is not always a bad thing, if the immune system is effectively helped in clearing pathogens, but patients should use caution to avoid excessive herxing. For those who are most seriously ill, even infra-red radiation from furnaces, etc, can cause problems.

The amount of energy is important
The only radiation which is important when considering 1,25-D or 25-D production, is radiation which carries considerable energy with it. For a given intensity of radiation, UV is the most energetic. The energy falls off with increasing wavelength (towards visible and infra-red) and the lower intensities of infrared energy do not cause problems.
The important thing about infrared energy is that it cannot be seen. Just because the heater coils do not put out visible light does not mean that the IR energy they put out is harmless. Even when thick, dark clothing is worn a little energy may reach the skin when direct sunlight falls on it (even though there is no light reaching the skin).
Sources of incident radiation
Sunlight (daylight) is the greatest source of infrared radiation.
Okay to use:
• Halogen lights… shield eyes with sunglasses.
• Computer monitors (flat screen or CRT)….shield eyes with sunglasses.
• TV or movie screens… shield eyes with sunglasses.
• Steam saunas with the heat generator hidden from view (do not raise body temperature more than two degrees).
• Fireplaces and heaters.
• Hot tubs (do not raise body temperature more than two degrees).
• Candlelight and fireplace light (don’t stare at light without sunglasses).
Do not use:
• Far Infrared (FIR) saunas
• Infrared heaters
• Saunas with electric coils under lava rocks (direct radiation, infrared)
• Bioptron light therapy
• Laser hair removal


It's okay to use steam saunas with the heat generator hidden from view. Be sure not to raise body temperature by more than a couple of degrees and not over 100 degrees. Raising body temperature too high could raise blood pressure and cause confusion, nausea, drowsiness or dizziness. Elevated body temperature can also increase herxing if it increases the tissue penetration of antibiotics.
When outside or exposed to daylight, it is essential to shield as much skin as possible. Clothing should be made with fabric that is dense enough to block most light energy (light and heat). Usually dark clothing works better (see PMID:1328275) but dense lighter fabrics have the advantage of reflecting some of the light. Thermal undergarments made with material such as Capilene are useful to block heat and wick perspiration.
Wear shirts with a high collar and long sleeves, trousers or a long skirt (such as flannel and denim), socks and shoes, a wide-brimmed hat and gloves (especially while driving). Long sleeve shirts and slacks, such as flannel and denim are good choices. A hat with a wide brim and neck covering should be worn; a hooded sweatshirt is an alternative.
Bright surfaces, like snow, concrete and sand, reflect UV and can nearly double the amount of light that reaches the skin and eyes. Nearby shade is not sufficient protection.
Indoor lighting to protect eyes (not skin)
A minority of patients need to cover house windows with thick material to keep out all light and lower incandescent lighting to a level of 30 lux (similar to low lighting in a romantic restaurant). Avoid fluorescent lights whenever possible. Even in a northern environment or if windows are shaded by trees or overhang, or are facing north, windows may need to be covered to block natural light from entering. A lux meter may be used indoors to measure artificial light intensity.
Ordinary window glass can block the UV wave lengths of invisible light, but it cannot block either the visible wave lengths of light or the infrared wave lengths of invisible light.
Window films (even those that claim to shield from UV and infrared rays), may not block enough light, unless using several layers in a northern window.
If necessary, windows should be covered with material that is dense enough to block all natural light. For example, blackout material for curtains can be purchased at fabric stores.
Light sensitive patients who can't shield the indoor environment from sunlight, should cover exposed skin and wear NoIR sunglasses.

Car windows
The effect of natural light through windows is most noticeable when driving in a car when the warmth of the sun's rays on skin is felt through the glass windows. Even if the windows are tinted, riding in a car is a common way to get too much natural light.

Computer use

It may be necessary to turn down the light on your computer monitor. Too much light stimulation to the eyes can cause psychological symptoms.

This website offers a free app, called f.lux, that automatically adjust the light level of your monitor or device.
Intolerable symptoms
Extra sun exposure can hit many patients really hard and in somewhat unexpected ways.
Although rare, some patients may be at high risk for an acute adverse event caused by sunlight exposure. High levels of 1,25-D affect muscle function, including the cardiac muscle, and sun exposure can be dangerous for people who have extensive Th1/Th17 inflammation, with even sudden death due to cardiac arrhythmia a possibility.
All patients should be instructed regarding adverse symptoms to report to their physician, and how to manage a significant adverse event should it occur. Detailed information on cardiac symptoms is in our Library of Information.

Experimentation with different adaptations to light will help patients discover their personal level of light sensitivity, which will gradually diminish during the healing process.
Patients and physicians should be alert for unexpected light sensitivity symptoms and know how to react to them. Patients, who develop intolerable light sensitivity and cannot avoid lights, will need to decide if they are able to make the needed lifestyle changes or must postpone Inflammation Therapy.

Recovery from light sensitivity
As the pathogens are reduced and the body heals, patients become less light sensitive and are able tolerate an increase in light exposure without having symptoms. Light sensitivity is reduced gradually so patients can still be susceptible to light exposure even after they notice a decrease in light sensitivity but this should be mild, compared to the initial reaction in the first few weeks or months.
In summary
  • Natural light: Protect eyes and skin.
  • Artificial light: Protect eyes. No need to cover skin.
  • Natural light exposure can cause an increase in symptoms, due to production of 1,25-D in the skin which increases inflammation and may cause rapid hormonal fluctuation. Sustained elevated 1,25-D can suppress the immune system.
  • Natural light and bright artificial light falling on the eyes may cause unpleasant neurological symptoms.
  • The main effect of light exposure for someone on nflammation Therapy is the intermittent symptom exacerbation which may push symptoms to intolerable.
Light sensitivity bullet points
• Sensitivity to sunlight and bright lights is also known as photosensitivity.

• Photosensitivity is how a person reacts upon receiving photons of light.

• Light sensitivity symptoms result from sun exposure to skin and sunlight or bright lights exposure to the eyes.

• Sunlight falling on skin may cause a variety of increased symptoms.
• Sunlight or bright light falling on the eyes may result in neurological symptoms.

• Light sensitivity is due to the Th1/Th17 inflammatory disease process.

• Light sensitivity may be exacerbated by the healing process and a decrease should be expected as healing progresses.

• Persons who are light sensitive prior to Inflammation Therapy will likely become more light sensitive during treatment.

• Persons who have no signs of light sensitivity may or may not become light sensitive during Inflammation herapy.

• Persons with limited inflammatory symptoms (suggesting early disease) are the most likely to be able to tolerate sun exposure during Inflammation Therapy.

• The amount of acceptable sun exposure will be based on individual tolerance of light sensitivity symptoms.

• The combination of Herxheimer reaction symptoms and symptoms due to sun exposure may be too difficult for some patients to tolerate.

• Patients need to learn to differentiate between symptoms due to light exposure and Herxheimer reaction symptoms. When in doubt, they should assume the symptoms are due to light exposure and reduce light exposure if symptoms are serious, e.g., cardiac in nature.

• Patients with pre-therapy levels of 1,25-D higher than 45pg/ml, those who have osteoporosis or may be at risk for osteoporosis, and those who didn't assess their 1,25-D, should consider that natural light exposure may increase 1,25-D to levels that promote bone resorption. They should weigh the risk/benefit ratio of natural light exposure against their need or desire for natural light exposure.

• The best protection from natural light exposure is provided by dark, tightly-woven clothing, and sunglasses that prevent all types of radiation (including infrared) from reaching the eyes.

• Sunscreen may provide some protection to reduce production of 1,25-D in skin cells and thus symptoms from natural light exposure.

• Sunscreen is best limited to skin that is unavoidably exposed.

• Stopping therapy may not eliminate light sensitivity. To avoid symptoms, continue the same level of light avoidance.

• A less-than-ideal compliance with light avoidance will be better than no therapy for many patients who cannot or will not change their lifestyle to avoid light exposure.

• Intolerable symptoms resulting from light exposure should be treated with diligent light avoidance, therapy medication adjustments and palliative medications. .

• Light sensitivity lessens as inflammation resolves during Inflammation Therapy.