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?
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 [1, 2, 3].
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 [1, 2, 3].
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 [4, 5].
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 [6, 4].
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 [7, 8, 9].
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 [7, 8, 9].
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 .
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.
The effects of blue light on 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) 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 .
Blue light therapy helps break down bilirubin into products that are easily eliminated .
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 .
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) [11, 12].
If bilirubin levels are only slightly high, therapy is optional. The treatment can be administered at home, but bilirubin levels must be monitored regularly .
Depending on the cause of bilirubinemia, bilirubin levels can be rebound after the treatment has stopped. Therefore, it is important to monitor them .
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 .
However, bilirubin is a powerful antioxidant. A very low-level can negatively affect newborns and cause chronic lung disease and brain injury .
2) 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 [15, 16].
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 light of different wavelengths [15, 16].
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 .
Blue light can also kill bacteria that cause diseases in the teeth and gums (Porphyromonas gingivalis) .
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) [16, 15].
Mice undergoing a short treatment with blue light overcame a life-threatening infection (P. aeruginosa) in a burn wound without tissue damage .
Blue light can treat infectious keratitis/eye inflammation (P. aeruginosa). Special care should be taken in adjusting the dosage to avoid retinal damage .
3) 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) .
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 [21, 16].
Blue Light and Other Skin Problems
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 .
The blue light helped reduce eczema lesions when applied locally three times a week for four weeks in 21 patients .
There is no evidence for the treatment of stretch marks with blue light.
4) 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 .
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 .
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) .
5) 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 .
Thirty night-shift workers using blue-enriched white light for one week had less working memory and omission errors and faster reaction times .
6) 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 .
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 .
7) 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) .
8) 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 .
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 [12, 34, 28, 39].
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 of 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 [40, 41].
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 .
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 .
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 .
A larger number of moles (a risk factor for the development of melanoma) were observed for patients who were treated with phototherapy as newborns .
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 [12, 42].
Blue light therapy only rarely caused headaches in patients being treated for fatigue .
Blue light therapy should not be used by people with congenital porphyria, a family history of porphyria, or using photosensitizing substances .
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.
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