Blue light is a part of visible light. It has a very important role in how our body adapts to light and dark cycles. Our modern lifestyle has increased our exposure to blue light. Despite its negative effects, the adequate use of blue light has several therapeutic benefits. Keep reading below to learn more about blue light therapy.

What Is Blue Light?

blue light therapy

Light is electromagnetic radiation of a variety of wavelengths within the electromagnetic spectrum.

There is both visible and non-visible light. Non-visible light includes ultraviolet (UV) and infrared light, while visible light includes the whole spectrum of the rainbow, including blue light. Within the visible light spectrum, each wavelength is represented by a color [R, R, R].

Of all the colors of the visible light spectrum, blue light (wavelength 446-477 nm) has the strongest impact on our physiology and circadian rhythm because the pigments in our skin and retina react to this wavelength [R, R, R].

How Does Blue Light Therapy Work?

A previous post describes in detail what blue light is and its effects on our body. This article focuses on how to take advantage of them to improve our health.

There are two main ways through which blue light affects our body: our eyes and skin.

Light exposure anchors human body functions to the rise and fall of the sun.

Blue Light and Our Eyes

When light hits the eye, it hits light-sensitive cells. These cells contribute to circadian rhythm entrainment by sending messages to the suprachiasmatic nucleus (SCN) in the hypothalamus. It coordinates light exposure with bodily functions through hormonal, involuntary nerve impulses, and feeding-related cues [R, R].

We can take advantage of these responses by controlling the time and kind of exposure to light, an approach called phototherapy. By looking at an adequate blue light source, we stimulate photoreceptor cells and generate a response in the hypothalamus. This helps with sleep disorders, depression, dementia, and sleepiness during night shifts [R, R].

Blue Light and Our Skin

In other parts of the body, like the skin, blue light activates proteins that contain light-sensitive molecules (porphyrins and flavones), increasing mitochondrial activity. This, in turn, increases oxidative stress [R, R, R].

Skin cells respond by releasing molecules that promote inflammation and control skin growth. Lesions caused by acne and some proliferative skin diseases improve when exposing only specific parts of the skin to blue light under controlled conditions [R, R, R].

The susceptibility of certain molecules toward blue light activation is used for therapeutic purposes. Scientists genetically modified rat heart cells to contain a light-sensitive protein (CatCh). Blue light pulses then helped control their heartbeat. However, this most likely cannot be applied to humans [R].

To take advantage of the effects blue light has on our bodies, we can expose our skin or eyes to an adequate source of blue light (a special LED lamp). The duration and time of day for the exposure will depend on the condition we wish to treat.

Blue Light Health Benefits

The effects of blue light in our body can be used to treat certain diseases. Photodynamic therapy is another method that combines blue light with drugs that activate within the blue light wavelengths.

1) Blue Light Therapy Helps with Jaundice in Newborns

Bilirubin is a yellow compound that is a breakdown product of hemoglobin in red blood cells. Bilirubin often accumulates in the blood of newborns causing jaundice (hyperbilirubinemia). In most cases, jaundice disappears after a few days. If it does not, and bilirubin blood levels are high, phototherapy is recommended to prevent brain injury risk [R].

Blue light therapy helps break down bilirubin into products that are easily eliminated [R].

The effectiveness of the treatment depends on the penetration of the tissues by the light waves. Therefore, lamps with output in the 460-490 nm region are the most effective [R].

Therapy can either be standard or intensive, depending on bilirubin levels. The standard therapy uses daylight, white, or blue fluorescent tubes. Meanwhile, intensive therapy uses special blue fluorescent lamps or LED lights (430-490 nm) [R, R].

If bilirubin levels are only slightly high, therapy is optional. The treatment can be administered at home, but bilirubin levels must be monitored regularly [R].

Depending on the cause of bilirubinemia, bilirubin levels can be rebound after the treatment has stopped. Therefore, it is important to monitor them [R].

Sunlight is a natural source of blue light. It is not recommended that sunlight is used for phototherapy due to the risks of exposing a naked newborn to temperature variations and sunburn [R].

Type 1 Crigler-Najjar syndrome is a hereditary disease where the lack of production of an enzyme causes hyperbilirubinemia (caused by mutations in the UGT1A1 gene). While liver transplant is the only definitive treatment, daily blue light therapy is used to manage the symptoms [R].

However, bilirubin is a powerful antioxidant. A very low-level can negatively affect newborns and cause chronic lung disease and brain injury [R].

2) Blue Light Is Antibacterial

Porphyrins are metal-containing molecules that react to light. When blue light interacts with porphyrins, it produces free radicals that damage bacteria. In other cases, it can activate mechanisms that make bacteria more virulent [R, R].

Gram-positive bacteria are more sensitive to blue light than Gram-negative. Bacteria that live in low-oxygen conditions are more sensitive to blue light because they have less antioxidant defenses. Since different species produce different kinds of porphyrins, they are vulnerable to a light of different wavelengths [R, R].

Helicobacter pylori, the bacteria that causes gastritis, can be killed by blue light. After a source of blue light was inserted into an endoscope into the stomach of 10 patients, it reduced the infection. However, days after the end of treatment, bacteria reappeared [R].

Blue light can also kill bacteria that cause diseases in the teeth and gums (Porphyromonas gingivalis) [R].

Blue light can decontaminate hospital and clinic rooms. It can kill bacteria that cause hospital-acquired infections (S. epidermidis, S. aureus, S. pyogenes, C. perfringens, E. coli, P. aeruginosa, and K. pneumoniae) [R, R].

Mice undergoing a short treatment with blue light overcame a life-threatening infection (P. aeruginosa) in a burn wound without tissue damage [R].

Blue light can treat infectious keratitis/eye inflammation (P. aeruginosa). Special care should be taken in adjusting the dosage to avoid retinal damage [R].

3) Blue Light Helps with Skin Problems

In some skin diseases like psoriasis, acne, and keratosis, immune cells at the baseline layers of the skin contribute to worsening symptoms. These cells (T cells) increase local inflammation and promote the formation of keratin-producing cells (keratinocytes) [R].

Blue light is anti-inflammatory and decreases inflammatory cytokine (IL-1alpha) production. High-intensity radiation causes T cell death [R, R].

Blue Light Improves Acne

Acne is a common inflammatory skin condition where fat production increases as a result of an increase in hormone levels.

When skin bacteria (Propionibacterium acnes) are trapped in the sebaceous duct, the skin swells causing red spots, blisters, and eventually nodules and cysts. P. acnes can be killed by blue light. Application to the skin of patients with mild to moderate acne also improves the wounds [R, R].

Blue Light and Other Skin Problems

Blue light therapy helps improve the symptoms of psoriasis, especially erythema [R, R].

Full-body blue light therapy helped treat atopic dermatitis and reduced itch in a study where 36 adults received five-day treatment cycles of radiation. Improvement persisted after two to three cycles [R].

The blue light helped reduce eczema lesions when applied locally three times a week for four weeks in 21 patients [R].

There is no evidence for the treatment of stretch marks with blue light.

Some studies have found that blue light helps prevent wound infections without damaging the skin, while others have found it either helps or interferes with the wound healing process [R, R, R].

4) Blue Light Helps with Fatigue

Blue light reduced fatigue and daytime sleepiness in a study (RCT) with 30 patients who had suffered traumatic brain injury when used daily for 4 weeks [R].

The blue-enriched white light helped regulate sleep disorders and increased alertness in a 9-week study with the 10 crew members of a polar station, who were under solar light deprivation [R].

In a study of 17 patients with restricted sleep, both dawn-simulating light and blue light used for two hours in the morning improved wakefulness and mood. However, only blue light helped regularize the circadian rhythm (by starting melatonin secretion and diminishing cortisol levels earlier in the evening) [R].

5) Blue Light Increases Alertness

Blue light therapy improves reaction times and improves working memory.

In a study of 21 patients, the effects of caffeine, blue light, and their combination on reaction times were observed. The combination helped patients react faster to visual stimuli. The use of caffeine made responses slower when distractions were included, while blue light improved the responses [R].

Thirty night-shift workers using blue-enriched white light for one week had less working memory and omission errors and faster reaction times [R].

6) Blue Light Helps with Depression

Bright light therapy treats seasonal affective depression (SAD). In a study with 52 adults with SAD who received morning therapy for 10 days, blue light therapy was as effective as a bright light in diminishing the perception of depression symptoms [R].

In another study with 24 patients with SAD, daily morning blue light therapy for three weeks was more effective than red light for improving symptoms of depression [R].

Daytime use of blue-enriched white light helps improve sleep and decreases depression and agitation in patients with dementia [R, R].

7) Blue Light May Affect Metabolism

By affecting the circadian rhythm, blue light can have different effects on our metabolism (energy production).

Blue-enriched light reduced sleepiness and increased glucose metabolism in19 adults exposed for three hours during morning or evening on otherwise dim light conditions. However, there was no effect on hunger (or hormonal measures of hunger) [R].

8) Blue Light May Protect Organs from Injury

Treating mice with blue light before oxygen deprivation in their liver and kidneys protected them from damage by preventing cell inflammation [R].


Excess exposure to visible light can have damaging effects on cells. Exposure to high levels (high intensity or long time) of blue light can be toxic; however, short-term use is safe [R].

Exposure to blue light at night has a negative effect on our health, due to the disruption of the circadian rhythm.

Blue light therapy is not recommended for newborns with isoimmune hemolytic deficiency, glucose-6-phosphate dehydrogenase deficiency, asphyxia, lethargy, temperature instability, sepsis, acidosis, or hypoalbuminemia [R].

Side Effects

In babies with cholestasis, blue light therapy may cause the “bronze baby syndrome”, where the skin and urine become a gray-brown color. The syndrome disappears after the treatment ends. Blisters can also appear [R].

A larger number of moles (a risk factor for the development of melanoma) were observed for patients who were treated with phototherapy as newborns [R].

Blue light therapy may cause retinal damage. Eye patches can protect the eyes of newborns, but small amounts of light might reach the retina. A greater number of harmless pigmented lesions are also possible long-term effects [R, R].

In adults, the skin treated with blue light can show from minimal to a mild increase in pigmentation, which disappears after some time [R, R].

Blue light therapy only rarely caused headaches in patients being treated for fatigue [R].


Blue light therapy should not be used by people with congenital porphyria, a family history of porphyria, or using photosensitizing substances [R].

How to Use Blue Light Therapy

People should only use intensive blue light therapy in hospital settings due to the risks of overexposure. Home devices are safe for the treatment of low levels of jaundice, seasonal affective depression, fatigue, and acne [R, R, R, R].

The devices used for acne treatment are hand-held blue LED lights. You should use them in close contact with the skin for short periods of time (3-4 minutes on each area).

Most lamps used for treating seasonal affective depression and for adjusting sleeping patterns use white light. Yet, there are a couple desktop blue light lamps on the market. You should use them in the morning for 20 to 30 minutes. You must position them at arm’s length and within the field of vision, and you should place the light within the peripheral field of vision.

Different types of delivery systems are being explored for patients with Type 1 Crigler-Najjar syndrome (who need full body exposure), as a blue light emitting mattresses or sit-up devices, to make the patients more comfortable and help them comply with therapy [R, R].

User Reviews

People use blue light therapy home devices mainly for the treatment of acne and for fatigue caused by seasonal affective depression.

Although the use of the device for skin treatment can be boring and requires dedication, the overall results are positive and worth the expensive equipment. However, it reportedly does not cure acne but controls it as long as the user follows the recommended frequency of use. A minority of the customers report no improvement in their skin conditions.

A home device for the treatment of psoriasis was recently (July 2017) approved for marketing in the USA. Users place the light on zones requiring treatment for 30 minutes daily. The use of the device is reportedly very time consuming and requires dedication. Most users report improvement in the treated areas.

Most customers are happy with the increase in energy and reduced fatigue experienced after using desktop blue light therapy lamps, while some find the light way too bright and report it causes headaches. Some people also felt no improvement in their mood or energy.

FDA Compliance

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.


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  • Mishi

    Dr Dieter Klinghardt reports that blue wave wavelength is the wavelength used by cells to communicate with each other so this kind of wavelength should be avoided at all costs. He uses the French scientist who discovered the AIDS virus as a reference for this statement.

  • carol close

    There’s some connection between sunlight and human health, autoimmunity or even cancer. – Not just with vitamin D, but also blue light from the sun! Researchers at Georgetown University Medical Center published a study this year showing that exposure to blue light and ultraviolet light from natural sunlight increases the movement of T cells, a key part of the immune system. Sunlight, therefore, is an immune booster. It turns out blue light produced by the sun can set off a different immune response. Blue light is on the shorter end of the wavelength of light we can see (not as short as UV rays, which are invisible to us). Because its wavelengths are so small, blue light can make it deeper into our skin, where T-cells are. Human skin has an abundance of T-cells, and blue light from the sun helps these cells circulate throughout the body. When these cells, called T-cells, flow around the body more effectively, they’re able to reach new infections more quickly, and stop them before they actually cause harm. In low levels like the kind we’d get outside, it turns out the blue light triggered T-cells produce hydrogen peroxide, which gives them a chemical kick in the pants, forcing them to circulate more effectively. These swirling T-cells are like guards patrolling the perimeter of a secure area: The more they circulate around, the more chances they have to spot any potential microbial threats, and eliminate them before they do any damage. The different blue light that comes from smartphone and computer screens, though, is “short-wave enriched,” meaning it’s at a higher concentration than what we’d get outside. This concentration can throw off your natural sleep cycle if you get too much of it at night.

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