Light therapy, sometimes called photo-therapy or photo-biomodulation, has been shown to be useful for maintaining health and well being. It is also a useful tool in recovering from several different conditions, including the following: treating and preventing dermatitis, healing wounds, nerve regeneration (including optical nerves), repairing peripheral nerve damage, preventing oral mucositis, healing venous ulcers, and improving retinal toxicity. white or natural light has been used successfully to treat seasonal affective disorder (SAD), menopause , and other, related depression, and erectile dysfunction.  Red light/infrared light is also showing promise regarding protective effects on neural damage associated with brain trauma, dementia, and Parkinson’s disease (1;2). Blue light has been used to treat infectious diseases (3).

The mechanism by which near infrared light works is based in its ability to increase energy production in cells while increasing blood flow. It activates cytochrome c oxidase (Cox), which absorbs 35% more red light.  Cox is a respiratory enzyme in cellular mitochondria.   Cox is produced during the last step of mitochondrial energy production.  Here mitochondrial membrane electrons and protons turn an oxygen (O2) molecule into two water (H2O) molecules (4;5).  This exertion also produces adenosine triphosphate (ATP) forming energy (4;6).   This is the energy formed within cells which is necessary for all living tissue to survive and engage in physiological processes. During this process ATP production can be inhibited by the displacement of O2 by nitric oxide (NO).  This is a potential problem as NO is healthy in small doses, but when it binds to Cox it inhibits mitochondrial respiration.  Near infrared light photo-dissociates, or cleaves, NO from Cox (freeing it from the mitochondria) which facilitates blood flow (6).  In short, the elimination of nitric oxide from mitochondria is thought to be the reason that red light therapy improves mitochondrial respiration (6;7).  Besides increasing ATP production, red light increases production of the following: reactive oxygen species (which in small amounts is helpful for healing etc.), intracellular calcium, and the release of nitric oxide. Activation of such transcription factors then lead to expression of the following: many protective, anti-apoptotic or cell killing factors; anti-oxidants; and pro-proliferation gene products (8).

Further, infrared light penetrates tissue better than visible light. Near infrared light intensity is only reduced by approximately half after passing through 2 mm of tissue.  This is far deeper than visible light can penetrate (4). Red light is different from sunlight as it is made of wavelengths of light ranging from 600 nano-meters (nm) to 950 nm and ultraviolet light has wavelengths shorter than visible light, ranging from 10 nm to 400 nm (9).

Injured tissues release more nitric oxide, which binds to cytochrome c oxidase (Cox), which absorbs red light at greater intensity. When NO bids to Cox It disrupts mitochondrial respiration, or the production of ATP.  This slows down cellular regeneration.  Near infrared light photo-dissociates NO from Cox, allowing No to go back into circulation.  This increases blood flow at the same time it allows for faster production of ATP in the injured cells, and so faster tissue repair (4;6).

Mechanism by which blue light works: blue light in the wavelength range of 405-470 nm has an antimicrobial effect. The benefit of blue light is that it works without causing additional changes to the cells being targeted, or to other, adjacent, cells,or molecules within the cells, which can cause a chemical change in other molecules, these are called exogenous photo sensitizers.  Microbial cells are sensitive to blue light, which has an antimicrobial effect, so it can heal wounds.  It can affect cell to cell communication via changes to blue light sensitive receptors in bacteria.  It can inhibit biofilm (found in the mouth) formation. When blue light has a higher radiant exposure, it exhibits a broad spectrum antimicrobial effect against bacteria (Gram-positive and Gram-negative types).  Blue light has been used successfully to treat H. pylori, oral bacteria, and P ache. it does this  by forcing the cells to produce free radicals or cytotoxic reactive oxygen species (3) via the photo excitation of intra-cellular compounds called porphyrins.  Blue light has successfully treated Helicobacter pylori infections of the stomach, pathogenic bacteria like Staphylocoocus aureus, and Pseudomonas aeruginosa.  It is less harmful to human cells than ultraviolet light (3).

Mechanism by which bright white or natural light works: it regulates melatonin levels by signalling the pineal gland to make more or less depending on the amount of daylight the gland is exposed too.  white light  can also improve vitamin D synthesis. Further, natural light has red light in it.  In bright daylight the near infrared spectrum, which penetrates tissue by up to 2-3 cm, may dissociate NO, promoting mitochondrial respiration (4). It has all of the other wavelengths in it, so it may have a similar, thought weaker, effect compared to stronger, artificial, light.

Testosterone, red light, sunlight, and white light. This is important as up to 25% of men over age 40 report sexual problems. Vitamin D production can be improved with light therapy (46). Low levels of vitamin D have been associated with lower levels of testosterone in both animals and humans (Mdmag).

Further, a lack of adequate vitamin D levels (improved with light therapy) has been found to negatively affect sexual desire (in women) (70). This may partially be due to vitamin D’s effect on blood flow, including that in the sex organs. Here vitamin D receptors in blood vessels respond to the vitamin by being more elastic, by working better (71).  If your sex organs are not getting enough blood they will not work optimally.  Sex drive is also based in hormonal health.  If your reproductive hormones, necessary for sexual desire, are out of balance it can cause low libido or sex drive.  Vitamin D is implicit in the production of testosterone and estrogen (64).

In a human trial, white light like that used for seasonal affective disorder (SAD) was used to increase testosterone levels and subsequently greater satisfaction sexually. In the study 39 men, who had been diagnosed with hypo active sexual arousal disorder or sexual desire disorder (lack of interest in sex) were randomly assigned to either an active light box condition or a much weaker light box condition.  The men had their testosterone levels measured as well as their baseline interest in sex. Before starting treatment, the groups averaged a score of 2/10 for sexual satisfaction. The average testosterone measurement was 2.1 ng/ml (average test group) to 2.3 ng/ml (average for control group). Both groups received early morning (30 minutes of exposure) treatment per day for two weeks.   After treatment the active light group saw their sexual satisfaction scores treble, to 6.3.  their testosterone went up to 3.6 ng/ml.   In comparison, the weak light (control) group had a slight increase in sexual satisfaction scores to 2.7.  Their testosterone levels remained at 2.3 ng/ml.

Light may encourage greater testosterone production because light therapy can inhibit the pineal gland (found in the centre of the brain), which then allows for greater testosterone production. This mimics light’s effect on reproduction in the spring and summer, when testosterone in males, including animals, increases (10).  This is echoed by animal studies (11).  Photo-stimulation has been shown to increase both testosterone secretion and testicular activity in animals, as well as serum levels of follicle stimulating hormone(FSH) which acts on the Sertoli cells of the testes to stimulate sperm production in males and luteinizing hormone (LH) which stimulates Leydig cell production of testosterone, Leydig cells act synergistically with FSH. It also improved testicular 17B-hydroxysteroid dehydrogenase (17B-HSD) activity, this enzyme helps convert hormone DHEA and steroid hormone androstenedione to testosterone. Similarly, low sperm motility (asthenospermia) may be treated with Low level laser therapy (LLLT). It has been shown in lab tests (in petri dishes) to increase sperm motility by up to 85%, while showing no damage to DNA (12).

Erectile dysfunction:  can be improved by red light/infrared light therapy.  This is because red/infrared light improves blood circulation and vascular dilation, allowing greater blood flow to the penis.  Red light can also improve production of nitric oxide (NO) and carbon dioxide (CO2), which are vasodilators, so these help with blood vessel dilation. If overly abundant NO disrupts cellular respiration and energy production by binding to respiratory enzymes in mitochondria, stopping them from using oxygen and producing energy.  Red light photo-dissociates NO from the process of cellular energy production, allowing cells to produce optimum energy, including in the penis.  Further, NO production in the penis leads, via interactions with guanylyl cyclase, to increased production of the substance cyclic guanosine monophosphate (cGMP) which is what causes the smooth muscle to relax, leading to increased blood flow, and erection, in the penis (80). Red-light also helps improve testosterone, which in necessary to get and sustain and erection.  Thyroid hormones also stimulate testicular functioning and the production of testosterone. (81).

In a small (39 men) human trial volunteers were either assigned to a placebo treatment or to laser light therapy. The latter involved two twenty-minute treatments per week, for six to eight weeks, with an 808 nm GaA1As laser light specially designed with two rows of five lights (150 nm). The median erectile function score for the treatment group improved from 13.5 to 20, in comparison the placebo/control group score went from 14 to 12.  After four or five treatments, many subjects in the light group reported experiencing morning erections (79).

Further, light therapy can positively impact or treat thyroid problems. Thyroid problems can be a cause of erectile dysfunction and treatment of it can help restore erectile functioning (82).

Skin health and appearance is improved with light therapy.  Skin responds well to near-infrared and red wavelengths of light (including low level laser therapy).  Red and near infrared-light effect skin at the cellular level, causing cells to regenerate, survive (when they would otherwise die), and proliferate as well as galvanize tissue repair. The mitochondrial chromophores in skin cells absorb the light’s photons, especially CCo or cytochrome c oxidase.  This galvanizes a cascade of events and bio-stimulation of numerous processes, including electron transport, the release of both ATP (adenosine triphosphate) and nitric oxide, improved blood flow, and increased production of reactive oxygen species (a good thing in this case).  Through these processes red/near infrared light enhances enzyme activity and activates diverse signaling pathways.  This leads to stem cell activation, and the healing of burns and/or repairs to damaged tissue (13) and the rapid (up to 200% faster).

Light devices, including those designed for in-home use, can treat fine lines and wrinkles, and  irregular pigmentation. For a faster result go to a professional for IPLs or intense pulse light sources. It also treats a condition called telangiectasia: widened venules of tiny blood vessels cause thread like red patters or lines on the skin.  It can also tighten skin as well as scars and photo-aged (sun damaged) skin.  Regarding skin damage due to UV light, red light can both treat this problem and protect against it.

Cellulite, or its appearance, has been treated with LED infrared irradiation during exercises on a treadmill. Here LED treatment, especially when combined with the contraction of skeletal muscles, leads to a thermal effect with higher circulation caused by a rise in muscle temperature can improve the supply of oxygen and the transportation and utilization of metabolic substrates (10).  This then leads to increased micro-circulation and better lymphatic drainage and subsequently an improvement in cellulite appearance and a reduction in thigh perimeter.  Cellulite is characterized by changes to lymphatic drainage and micro-circulation, and dysfunction cutaneous and adipose tissue that has a fibrotic reaction (10).

Red light can even help to treat disorders of pigmentation like vitiligo (when skin loses colour, appearing white or depigmented).  this is due to the pigment cells or melanocytes, being destroyed by the disease). Here it stimulates the proliferation of melanocyte while reducing de-pigmentation by slowing autoimmunity. It can also help treat diseases of inflammation like acne (especially in combination with anti-bacterial blue light) and psoriasis, as well as the cold sore virus or Herpes Virus Lesions.  Keep in mind that the oral variety responded better than the genital variety to light therapy (13).

You can also use light therapy to produce more collagen using either red light or infrared light, or a mixture of both. The first, red light, slows production of enzymes associated with collagen breakdown and increases fibroblast production. Red light (free from UV rays) uses non-damaging light wavelengths known to increase collagen.  The second, infrared light, helps increase production of type one and three collagen specifically, as well as elastin.

Preparing the skin is important to the success of using light therapy. Remove all makeup and oily substances.  Maintain the equipment properly.  Strength is an issue depending on what the light is used for.  Low fluences (390 nm to 690 nm) and power densities are used for superficial tissue.  While longer wavelengths (600 nm to 1100 nm) are used for deeper tissues.

Light therapy has successfully been used for pain management and healing: as well as other ailments.  For instance, it has been used successfully to treat arthritis, to increase blood flow, and wound healing time, and even to improve endorphin levels (83).  In one study, back pain was proven to be reduced by 50% in, after seven weeks of using an infrared emitting belt with light in the spectrum of 800 nm to 1200 nm. This was in comparison to a placebo group, which reported a 15% reduction in pain. This type of light is protective against ultraviolet light as it has an antioxidant effect (83).  In another study, on knee osteoarthritis, 18 subjects were given 12 sessions of low level light therapy, at three a week, for four weeks. The device used a pulse radiation mod with wavelengths varying between of 810 nm and 50 nW power to 890 nm, with 30 nW.  the results showed a significant reduction in nocturnal/nighttime pain and pain when walking or going up stairs, there was a significant reduction in these factors, as well as in measurements of: knee circumference, distance between hip and heel, and knee to horizontal hip to heel distance (14).

Irradiation with NIR light promotes nerve regeneration via enhancing oxidative processes on the mitochondria. Its bio-stimulating effect have been shown to help the following: wound healing, bone repair, cell growth, and reducing inflammation.  An example of this is that red light has even been shown to help heal nipple trauma in breastfeeding women (1). In a small study of five individuals with wounds, all achieved full healing, control of any infection and control of any discomfort.  The treatment time lasted one to eight weeks, depending on the wound, and a LED-LLLT system with 830 nm of light, with 100 nW of power was used. It was considered that the LLLT considerably accelerated all of the wound healing, regardless of wound type. It was also considered easy to use, well tolerated by all patients, and pain free (15).

Light therapy can help treat diabetic peripheral neuropathy (the disease or dysfunction of peripheral nerves, causing numbness or weakness). It does this by improving plantar sensitivity, or sensitivity to touch of the plantar area of the food, which is usually decreased in diabetics.  Light therapy was shown to help with (short-term) improvements to tactile sensitivity (16).  It has also been used, in conjunction with muscle stretching exercise, to treat myofascial trigger points.  It (830 m) also helps improve circulation and joint range of motion, pressure sensitivity, and pain in patients with osteoarthritis of the knee (10).

Light therapy to reduce inflammation:  Low level laser therapy has been used successfully to lower inflammation in muscle and sub-plantar tissues as well as edema or swelling (17). This is important as inflammation causes pain as well as damage to tissues and increases the likelihood of developing inflammation related problems (depression, cancer, heart disease, arthritis, diabetes, thyroid problems etc.). When the skin is exposed to near infrared and red wavelengths the skin cells’ mitochondrial chromophores absorb the light photons (13).  This leads to many signaling pathways in the nervous system being stimulated (including stem cells, which repair tissue damage) as well as the transport of electrons in the cells, the release of ATP or adenosine triphosphate nitric oxide, an increase in blood flow, and an increase in the production of reactive oxygen species (13).  All of this avoids tissue damage, reduces pain and inflammation and increases healing and damage repair within tissues and nerve cells. It is now thought that red light specifically can modulate cytokines from cells, including macrophages, lowering inflammation (18).

Inflammation is associated with osteoarthritis or OA, it also causes degeneration of articular tissue. This is as OA triggers PG or prostaglandin E2 and pro-inflammatory cytokines, types of inflammatory markers.   PBMT or photo-bio-modulation therapy, a type of low level light therapy, has been found to be more effective in moderating inflammatory process of OA then drug therapy, NSAID or topical non-steroidal anti-inflammatory drugs, and physical exercise (18).

Besides being about to treat OA related inflammatory indicators or mediators (cytokines TNF-a and CINC-1), it can help treat OA in the following ways: reduce the protein and gene expression of bradykinin receptors (B1 and B2), associated with pain, and acute and chronic inflammation, and increase the stimulus response threshold of pressure in an experimental model of acute osteoarthritis (19). In this way it can help treat OA related increased sensitivity to pain, called hyperalgesia.

Light therapy for exercise intolerance/recovery: light emitting diodes, applied to skeletal muscles both before and after exercise have been used to reduce exercise intolerance and fatigue. It also improved the following: functional capacity regarding time, distance covered, and speed of exercise (20).

Dental health: may benefit from light therapy devices. Blue LED or dental halogen curing lamps are specifically designed to fit into the mouth.  Periodontal disease leads not only to loss of gum recession and tooth loose, but are associated with other, systemic, diseases.  These devices can kill certain bactria found in the mouth (actinomycetemcomitans, Fusobactrium nucleatum, and Porphyromonas gingivalis) in 15 to 60 seconds, but only if in a certain state (biofilm) in other states (planktonic state “2) it is helpful in reducing pathogens only (21). Keep in mind that blue light may activate reactive oxygen species after gum surgery, which could be damaging to gum tissue after surgery specifically.

Light therapy for weight loss: light therapy has many applications regarding weight loss.  Near infrared-light can be used to help burn more fat.  White light in the morning may help regulate the hormones leptin and ghrelin.  Leptin is the hormone your fat tissues produce when eating to signal the brain that   enough energy producing calories have been restored and you can stop eating.  Ghrelin is the hormone produced in the stomach to signal the brain that you are hungry.

Red light is now being considered as “an innovative, non-invasive, easy to use, safe, and promising method for controlling obesity and abdominal fat” (1, pg.5). Near infrared light in wavelengths of 600-1000 nm wave lengths have been shown to be effective for weight lose.

Infrared light at 850 nm at 100 mW was shined on the thighs of postmenopausal women aged 50 to 60 years old as they walked on a treadmill (10). In this study a thermal imaging camera was used to record the activity in the fat cells of the skin the light was applied too.  The active light group were compared to another, similar, group of women walking on a treadmill, but without light.  The active or light group had a significantly higher body temperature then when they started exercising as well as in comparison with the control group, who’s body temperature was lower than when they started exercising. This is because the exercise only group started sweating at about 10 minutes into the activity, and this cooled their skin.  The active group also sweated, but the infrared light was absorbed by the water on their skin and then warmed it. Further, infrared light increased temperature as it improved the micro-circulation via the vasodilator reflex, angiogenesis (when new blood vessels form from pre-existing ones) was also present (10).  These reactions were probably due to the action of infrared LEDs on nitric oxide or NO.  Here LED treatment, especially when combined with the contraction of skeletal muscles, leads to a thermal effect with higher circulation caused by a rise in muscle temperature can improve the supply of oxygen and the transportation and utilization of metabolic substrates (10).

Red light in the form of a near infrared (NIR) light emitting diode (LED) belt (NIR-7 Healthcare, Korea) with wavelengths of 700-960 nm worn on the abdomen during aerobic exercise can assist with weight loose.  In a human trial of overweight adolescents, the subjects walked on a treadmill for 45 minutes per day, at a VOX max of 50%, three days per week. Half the subjects wore the belt with active lights, half wore inactive light belts.  Those who wore the active light belts experienced an average reduction 0f 5.02% on their BMI (body mass index) score as well as a significant reduction, 5.65% (controls only lost .84%) in their waist circumference and overall 5.55 of body fat (controls lost none) (1). These findings echo other study results (1).

The reason red light therapy may work for weight loss lies in the effect it has on the production of energy within fat cells. The near infrared/red light, at a specific wavelength and wattage, penetrates the skin and surface fat to reach deeper adipose tissue.  The tissue’s cells’ photo-receptor molecules absorb the light.  In the molecules light improves cytochrome C oxidase functional activity, this then promotes mitochondria’s oxidative metabolism, all of which result in increased ATP production, and result in more energy availability for fatty tissues to be metabolized (1).).  In short, mitochondria, which is in cells, has cytochrome C oxidase, which absorb the light.   The cytochrome experiences an acceleration in mitochondrial energy, leading to more energy being available for exercise and thus the improvement in calorie burning and body weight/fat reduction. Basically, in this study the belly fat became a fuel for ATP production, and this fuel was used during the aerobic exercise. Further, red light helps improve endurance during exercise, it delays fatigue and increases tolerance (1).

Regarding appetite related hormones ghrelin and leptin, it has been shown in studies on sleep deprivation that narrow band morning light exposure can modulate the production of these in people. When a person gets less than eight hours of sleep a night they usually produce more ghrelin (up to 28% more), and less leptin (up to 19% less).  Ghrelin is produced in the stomach to signal hunger, and leptin is produced in the fat to signal satiety (fullness). In short, too little sleep leads to overeating. In animal studies melatonin has been known to decrease leptin concentrations, so it is possible that the subjects who were not getting enough sleep or morning light were experiencing an increased production of melatonin, or a disruption of the bodies ability to produce it at appropriate times.  In short, using light (be it natural, white, blue, green, or red) in the morning significantly impacts sleep deprivation related hunger. Those sleeping five hours who were exposed to morning light, be it red (60 lux/6 nm), green (532 nm), or blue (475 nm), had significantly decreased concentrations of ghrelin and increased concentrations of leptin (22).

Sleep hygiene: can be assisted with 30 minutes of bright light (11 kilolux) in the morning (38). This exposure helps signal individuals to awaken at an earlier time (before 8 am) and to go to bed at an earlier time (before 12 pm). This subsequently helps with weight management and psychological wellbeing.  A human trial of white light/bright light shined into the eyes early in the morning, combined with sleep shifting (where you change the time of going to sleep and getting up) to an earlier hour helped peri-menopausal women sleep better within two weeks of starting the treatment (9). The treatment shifted the women’s melatonin related circadian rhythms.

Thyroid problems can be improved with light therapy: specifically, red light. Thyroid problems should not be overlooked as they lead to other problems, including anxiety and depression.  Red light/near infrared light can help to stimulate Vitamin D production, which positively impacts the thyroid gland’s functioning.

The synthesis of steroid hormones, including progesterone and testosterone, are affected by the thyroid. These then effect feelings of vitality, emotionality, and even the libido/sex drive.  The thyroid also influences metabolism (including food intake, body weight, and activity), heart rate, blood pressure, and body temperature (23).

Chronic autoimmune thyroiditis or CAT is the most common type of hypothyroidism.  CAT often requires lifelong drug therapy, with levothyroxine or LT4 (24).  Low level laser light therapy or LLLT (830nm, with an output power of 50mW and a fluence of 707 J/cm) has been show to be an effective adjunct to medication for thyroid treatment. In one study LLLT was shown to improve thyroid functioning while reducing thyroid autoantibodies or TPOAb mediated autoimmunity.  This a good thing as TPOAb can harm the cells of the thyroid gland.  TPOAb also increases thyroid echogenicity, which is used as a measure of thyroid gland health, with lower numbers being an indication of better health.

In one study, 43 individuals taking levothyroxine for CAT were given either ten sessions of low level laser therapy or a placebo treatment that did nothing. The drug treatment was stopped 30 days post treatment.  The subjects thyroid functioning was then tested nine months later by estimating the amount of prescription medication needed to achieve normal concentrations of T3, T4, free T4, and thyrotropin.  The results indicated that in comparison to the placebo/control group the active participants required significantly less of the drug levothyroxine or, in some cases, none at all, to treat their hypothyroidism.  In fact, 48% of the test subjects experienced normal thyroid hormone levels even though they had not been taking medication for nine months (24).   Subjects in the active condition also experienced a normalizing of thyroid volume, which is an indication that the thyroid gland has returned to a normal, or healthy, state.

These subjects’ autoimmunity was also tested, by measuring the thyroid autoantibodies (TPOAb and TgAb) levels. The test group, in comparison to the placebo/control group, showed 49% lower TPOA.  The test group also experienced a 19% higher echogenicity or IB, meaning to bounce an echo or return the signal in ultrasound exams.  This is good as the higher the result, the healthier the gland.

In another study 15 subjects with CAT, and taking levothyroixine (LT4), were given 10 sessions of LLLT (830 nm, output power of 50 nW), at a rate of twice per week for five weeks. These people were given ultrasound studies before treatment started and 30 days post final treatment, when medication was also stopped. The results show that all 15 subjects had a reduction in the amount of LT4 required, and 7 people, or 47% of the group, no longer required any LT4 through to the 9-month follow-up.  Those that did need medication needed lower doses. The TPOAb levels were also reduced by 39%, and the parenchymal echogenicity was increased by 22% (25).

Postsurgical hypothyroidism Is also helped by red light in the form of low level laser light (LLLT). A study showed that   LLLT can lower medication dosages required to treat hypothyroidism by 50 to 75%.  Here Tg and TPO antibodies were also lowered after treatment.

Hypertrophic forms of autoimmune thyroiditis can also be helped by LLLT (26;77 762;78 763).  In a two year study of both subclinical and clinical hypothyroidism or euthyroid, all subjects experienced the following after four courses (10-15 treatments per course): had a lowering of TSH and TgAb; the subclinical population 92% of subjects had a delay in developing clinical hypothyroidism; 40% of all subjects had a return to normal measures of the thyroid stimulating hormone, indicating either prevention to the disease state (in subclinical subjects) or a regression to normal (in clinical subjects).

Hypothyroidism comorbid with heart disease can be assisted by LLLT.  This is important as many heart patients don’t take appropriate doses of thyroxin for fear of its negative impact on their heart condition. In a placebo-controlled study, the subjects getting LLLT experienced significant (TSH lowered by 50% and T4 increased by 95%) improvements to their thyroid hormone levels and improvements (lower by 2.14%) to their cholesterol levels, going from 8.23 to 6.09.  Keep in mind that these improvements were seen at the three-month mark.  Thyroid hormones influence cardiovascular or heart functioning, body temperature regulation and metabolic rate (23).

Depression, anxiety and other mental health issues:

Light therapy, especially blue light, has recently been proven more effective than anti-depressants in treating depression (27) and combining light therapy with antidepressants was even more effective. Light treatment for depression (seasonal and non-seasonal) can be used as a stand-alone treatment or in conjunction with other treatments. For instance, in one trial it was shown to be slightly, (70% vs 65%) more effective than the medication fluoxetine (28). Both blue (in animal studies) and red (human studies) light therapy have been clinically proven to increase dopamine levels (29).

White light treatment alone has been shown to be beneficial for depression. In a human trial white light shined on depressed individuals before they got out of from bed in the morning produced meaningfully lower scores, in comparison to pre-treatment scores, on both the Beck depression rating and the Hamilton depression ratings scales (28). Bright light in the early morning has been shown to improve sexual functioning (increased libido and sexual activity) which is a known sign of depression (30). Regarding increased testosterone in males, bright morning light, (1 00 Lux) from 5 to 6 am has been shown to increase luteinizing hormone (LH), also called interstitial cell-stimulating hormone (ICSH), which in turn stimulates Leydig cell production of testosterone in men. In women LH triggers ovulation.

Red/near infrared light (NIR) therapy is showing promise as a depression treatment in humans. For instance, in one study (31) all of the subjects showed a significant change in depression one week after the final treatment (18 treatments, 20 minutes each).

Regarding winter or seasonal depression, individuals who are exposed to bright white light with a 2500 lux intensity for two hours daily will get relief from symptoms of depression. Those who were exposed to light in the early mornings had the best experience (53% of participants), followed by those exposed in the evenings (38% of participants); the least responsive were individuals exposed to light at midday (32% of participants).   Using the device more than once per day did not enhance the effect. Some people see a difference after only one week of using a light device, others need two weeks (28). If you can’t arrange two hours of daily bright light exposure, using a low light (one that peeks at 250 lux) to simulate dawn exposure (one with a timer that goes on while you are asleep) so that you get 1 ½ hours of low level light exposure can improve winter depression can help. In a study of such devices, 40% of subjects reported improvement of symptoms (28). Those individuals with hyper-somnia (sleep too much) had the greatest reaction.

This response to white light exposure may be the result of bright white light’s ability to mimic sunlight’s effect on melatonin secretion. Regarding winter depression, if the individual is exposed to bright fluorescent light (Vital-Lite) of 2000 lux for three hours after waking up (say 6 am to 9 am) and again in the late afternoon for three hours (say from 4 pm to 7 pm), the individual’s photo-period (hours of daylight) will lengthen to 13 hours, which mimic springtime or the spring photo-period. During this time of light exposure, melatonin levels will be reduced by 88% between the mid to late afternoon hours (say 1 to 5 pm). It is theorized that melatonin production is decreased in those suffering with psychiatric problems, especially depression. Depression is linked in some to a dysregulation of norepinephrine and serotonin containing neurons (and their receptors) in the CNS. Changes in melatonin production may indicate a problem with these systems as melatonin (32).

Melatonin is linked to serotonin and dopamine production. Melatonin is a monoamine made from tryptophan. Converting tryptophan to Melatonin involves several steps, including making serotonin. So, serotonin levels impact melatonin levels, and vice versa. If a person is experiencing a deficiency in serotonin they may also experience a deficiency in melatonin. Also, when the brain cells targeting melatonin take it up, they can take up too much serotonin, which may result in a lose of serotonin (33) that is necessary for emotional well-being. So, it can become a negative feedback loop. Regarding the feel-good neurochemical dopamine, the lack of which is associated with depression, melatonin has been shown to inhibit the release of dopamine, this occurs in the CNS or central nervous system, specifically in the hippocampus hypothalamus, medulla-pons, and the retina as well as the striatum (34).

Regarding peri-menopausal and postmenopausal thyroid function, melatonin helps reverse this by changing gonadotropins to reflect those of younger women (32). Gonadotropins are hormones that, in women, stimulate the release of follicle stimulating hormones (FSH) and luteinizing hormones (LH) from the pituitary gland. In the female body, LH stimulates the production of testosterone, which is then converted to estrogen. FSH stimulates the egg follicles to mature, these follicles will eventually produce estrogen. Female sex hormones are neuromodulators, they play a significant role in controlling the dopamine neurons, called nigrostriatal, found in the area of the brain linked to cognitive processes, called the Substantia nigra.  In animal studies (female rats and primates) subjects who had their ovaries removed experienced a 30%, or higher, loss of dopamine cells (35).  This is very important as neurotransmitter dopamine is produced in these cells.  So, sex hormones, by way of the Substantia nigra, are central to cognition, emotion, and movement.  The neurons in the Substantia nigra travel to the frontal lobes (attention and executive function) and the area of the brain associated with motor control.  If there is a death of neurons in the Substantia nigra, cognitive problems, and loss of motor control, will result (36 580).   Further, estrogen also intensifies the effects of norepinephrine (adrenaline in the brain) and serotonin.  It does this partly by decreasing the monoamine oxidase (MAO) activity in the central nervous system (CNS).  MAO breaks down serotonin and norepinephrine, so estrogen slows this process down, leaving the neurotransmitters active longer. This may explain the antidepressant like effect of melatonin (if given/taken at the right time of day) in peri-menopausal and menopausal women (32). In a human study of natural morning light, it was found that post menopausal women who had less morning window covering and more morning light experienced less depressed mood (37).

Regarding antepartum depression and postpartum depression, women who experience antepartum (still pregnant) depression who were exposed to light therapy for three weeks reported a 49% reduction in symptoms. Women who were treated for postpartum depression with light therapy reported a 75% reduction in symptoms (28).

Anxiety is helped by light therapy.  As the seasons change light, which helps signal hormonal fluctuations in the body change.  Some of these influence cycadean rhythms, which also change.  In short, people tend to experience a shift in sleep patterns, going to bed, and to sleep, at later times. This then shifts circadian rhythms. Without proper sleep, individuals who are genetically predisposed to being light sensitive regarding hormones, experience more anxiety.  Bright light (11 kilolux for 30 minutes) in the morning hours can impact the fear centre of the brain, by lowering its activity. The light improves communication between the amygdala, which has a pertinent role in how people react to their environment and shapes anger and fear responses, and prefrontal cortex (the frontal lobe controls the amygdala’s activity), lowering its reactivity and improving communication.  This allows for greater control of the fear response (38).  Keep in mind that there can be a genetic component to how well individuals react to light.

Bright white light at 3,000 lux, with an exposure of 20 minutes per day, for three consecutive days, has been shown in a clinical trial to reduce anxiety in low-anxiety suffering adults (39). Blue light exposure increases the production of the neurochemical serotonin, associated with feelings of happiness and well-being.  It may strengthen and stimulate the areas of the brain responsible for processing emotion and language.  This in effect enables better handling of stressful situations and greater mood regulation (40). Regarding dopamine, both blue and red light stimulate the production of this neurochemical, the lack of which is associated with high stress (41), chronic mild stress, anxiety, and depression (42).  Light stimulates dopamine in the area of the brain called the nucleus accumbens (29).  This is important as low levels of dopamine are associated with high stress (41) and this area of the brain is associated with reward and learning as well as addiction and depression.

The nucleus accumbens is the area of the brain responsible for motivation, learning/reinforced learning (including conditioning through transference from one experience to another), actions based on how important the reward is (reward incentive salience), positive reinforcement and pleasure, as well as sleep hygiene and impulsivity (including self control to obtain goals efficiently), fear processing (aversion) and the placebo effect. It can also affect motor control and is involved with integrating emotional information with intellectual information as well as integrating new experiences into memory in a manner meant to guide subsequent decisions (43).

Ideally you would get enough light naturally, by walking outside in sunlight for 15 minutes a day. Alternatively, you can buy an inexpensive light box at most retailers or online.  Another option is installing full-spectrum high-quality (fluorescent) light bulbs in your home and place of work.  Keep in mind that blue light can harm your eyes, so don’t look directly at it.  Also, avoid blue light at night as it may affect the ability to go to sleep (including TV and tablet screens).   If you purchase a blue light box place it on a high enough surface to allow the light to hit the lower part of the eye, as this is where blue spectrum light naturally is absorbed (44).

It is recommended that those who suffer from winter depression start using light therapy at the first signs of winter, as this may prevent the onset of seasonal depression (28). Natural light from walking out doors (1 hr per day) has also been shown to positively impact depressive symptoms, this activity can change melatonin production in a positive way regarding mood as well as lower stress hormone Cortisol (28).

Light therapy (especially blue spectrum light) increases serotonin. When possible walk out doors in bright sunlight for 15 minutes a day (27;40).  Otherwise, you can buy an inexpensive light box.  Keep in mind that blue light can harm your eyes, so don’t look directly at it. Bright light therapy should not be used by those with eye diseases, and those using medications deemed photo-sensitizing (45).

Avoid blue light at night as it may affect the ability to go to sleep (including TV and tablet screens).   If you purchase a blue light box place it on a high enough surface to allow the light to hit the lower part of the eye, as this is where blue spectrum light naturally is absorbed (44).

Bright light can induce mania (rarely), migraines (1/3 of migraine sufferers).

Vitamin D: production can be improved with light therapy (46). Commercial tanning beds may be effective at improving vitamin D production in the skin (47).  But, these have also been linked to skin cancer.  Many commercial tanning businesses offer red light only tanning beds. Vitamin D deficiency is an important issue.   It is linked to obesity and diseases of the bowel like celiac disease, inflammatory bowel disease, and chronic diarrhea (46), as well as increased risk of type II diabetes and mental health issues.

Vitamin D deficiency is on the rise. In the United States, only 23% of the population is getting the minimum amount of vitamin D needed to maintain general health and wellbeing (48). This means that 77% of the U.S. population may be deficient.  In Canada, 49% of adults aged 20-39, and 32% of those 40 to 59, are deficient (49). Only 35% of all Canadians, regardless of age, take D supplements.  Of those who do take them, 85% have enough vitamin D in their systems for optimal health.  Only 59% of non-supplement users could show the same.  In Canada vitamin D levels fluctuate seasonally.  40% of all Canadians fail to get enough D in the winter, and 25% fail too in the summer months.

Red light and vitamin D for depression: medical tests for vitamin D deficiency include a depression inventory (50). This is as depression has been associated with low levels of vitamin D (46). This may be due to the necessity of vitamin D for the production of the neurotransmitters serotonin (51) and dopamine (52), and it may impact functioning of the hypothalamus and neuroendocrine system.  Vitamin D depletion is associated with higher scores on depression inventory’s (CES-D, HADS & Beck). There is an overall improvement on scores of happiness, depression, mood, sleep quality, self-esteem, and general well-being when Vitamin D is mixed with outdoor activity, called eco-therapy, involving an increase in natural light exposure, (46).  In fact, eco-therapy alone has shown to improve depression, self-esteem, and lower tension.

Red light, vitamin D and thyroid problems: A lack of vitamin D can contribute to parathyroid disease as parathyroid hormone, PTH, is derived from vitamin D. Parathyroid disease may occur if there is a vitamin D deficiency. Parathyroid hormone, PTH, is derived from vitamin D and it is needed by the body to absorb calcium into bones and helps to make them.  PTH also moves calcium out of bones and into the blood.  PTH also helps the intestines’ to properly absorption phosphorus and calcium from food (48). These are “the supply minerals for the skeleton” (48, pg. 20).

This is important to bone health as the parathyroid hormone, or PTH, helps maintain levels of calcium.   PTH can also stimulate the formation of new bone, and the removal of older, weaker, bone matter (48).  So, parathyroid disease may occur if there is a vitamin D deficiency.  There is a gland beside the thyroid gland in the neck that produces the parathyroid hormone.  This hormone directs the kidneys to stimulate calcitriol (hormonally active metabolite of vitamin D) production (increasing intestinal absorption of calcium from food sources) or to reserve calcium. This hormone in short is what controls the amount of calcium circulating in the blood.  If there is even a slight change in the amount of calcium in the blood the PTH gland will increase or decrease production of this hormone concurrently. An excessive amount of calcium in the blood can cause the condition hypercalcemia, or too much calcium in the blood (53;54) leading to the following: kidney problems (excessive thirst & urination, and stones), bones (fractures, pain, osteoporosis), muscle (cramps, twitches, weakness) and heart problems (cardiac arrhythmia, fainting, palpitations), stomach problems (constipation, decreased appetite, nausea, pain, upset, vomiting), cognitive problems (coma, confusion, depression, fatigue, headache, irritability, lethargy, memory loss) and excessive blood clotting.  Hypercalcemia can be caused by overactive parathyroid glands (especially in women 50 plus), medications like diuretics and lithium, lung diseases and lung cancers including tuberculosis and sarcoidosis. Breast cancer and cancer of the blood can also cause this.

Keep in mind that too much Vitamin D or too much calcium (from supplements or antacids, which are the third most common cause of hypercalcemia in the U.S.) can also have this effect.

Diabetes: it can be hypothesized that red-light therapy can help treat latent autoimmune and type II diabetes. This is as red light helps better synthesize vitamin D, the supplementation of which is associated with reduced risk of both Latent autoimmune diabetes in adults (LADA), which is a hybrid or mix of type I and II, and type II diabetes.  Many immune cell types (B and T cells for instance) have vitamin D receptors.  Vitamin D in an active form, as the metabolite 1.25(OH)2D, has the ability to control immune cells’ inner workings and production/growth. In both type II and LADA diabetes vitamin D may affect the way B cells in the pancreas work.  This is done by 1,25(OH)2D, found in vitamin D, binding to vitamin D receptors in B cells (55).  Poor B cell functioning is also associated with insulin resistance, both types of B cell malfunctioning predict the onset of Type II diabetes years before its final onset (55).

Further, vitamin D increases insulin action by stimulating insulin receptors expression causing an improvement in glucose transportation.  In type I diabetes vitamin D may help to treat the condition by modifying T cell diversity.  T cells are white blood cells that protect against illnesses.  In Type I Diabetes T cells are signaled to destroy cells in the areas of the pancreas (Islets) that produce insulin (56).  In Type II diabetes T cells are implicit in the patho-genesis of the disease.  In this case T cell are necessary for metabolic inflammation and insulin resistance to develop (57).

Red light for menopausal symptoms.  As women move through the menopausal transition it may become harder for their bodies to activate vitamin D (58).  This is as the sex hormone estrogen, which can become inconsistent during pre-and peri-menopause, helps to increase the activity of the enzyme that in turn stimulates vitamin D production.

Many symptoms of vitamin D deficiency mirror those of peri-menopause or menopause. These include fatigue, hot flashes, infrequent menstrual periods, weight gain, and dry mouth (50). Other symptoms of vitamin D deficiency are depression or irritability, vaginal dryness, and during the premenstrual period symptoms of premenstrual syndrome (PMS). The last are: breast tenderness, limb’s swelling up, and bowel problems (59).

Red light for bone health: Other symptoms of vitamin D deficiency include osteoporosis (60), and joint or back pain (50), bone pain, problems walking, and frequent falls (46). Further, Vitamin D increases bone mineral density (61; 62) so it is an important factor in preventing and treating the diseases Osteomalacia and Osteoporosis, both of which cause fractures, deformities, and bone pain (48).  Vitamin D helps maintain cartilage. Vitamin D also can decrease the risk of falling as too little vitamin D may be signified by a lack of balance (62).  Vitamin D also helps in the absorption of calcium (63).  This is important as the production of estrogen, which helps move calcium into the bones and soft tissue, is greatly disrupted during the pre-and peri-menopause phase and markedly reduced and after menopause (48).

Red light may help female reproductive problems: Vitamin D, in the form of calcitriol, is a hormone which effects many systems in the body, including the reproductive system. Vitamin D deficiency has been linked to many obstetric and gynecological problems (64) including fertility impairment, uterine fibroid’s, endometriosis, and poly cystic ovarian syndrome.   Vitamin deficiency and insufficiency (a milder form of deficiency) contributes to sexual dysfunction.  It is also implicit in vaginal dryness, infections, low sex drive, and thinning of the uterus.

Vitamin D deficiency has been linked to hormonal imbalances, including premenstrual syndrome (PMS). This is important as 85% to 90% of premenopausal women report experiencing PMS symptoms (physical or emotional) regularly (65). Of these women, up to 20% have symptoms that meet the clinical definition of PMS.  And, up to 8% of premenopausal women may meet the clinical criteria for premenstrual dysphoric disorder, which is associated with an inability to carry out the everyday functions of life (65).   Further, treatment with vitamin D has been show to regulate irregular menstrual periods and to improve ovulation.  This may be of help for women who have Poly Cystic ovary syndrome, or PCOS (66).

Regarding vaginal dryness, vitamin D, in the form of a vaginal suppository, can help treat vaginal dryness, thicken vaginal skin and improve vaginal pH balance. After 8 weeks of treatment of this type vaginal pain, during sex or when the tissue is touched, should be reduced.  The color of the tissue should improve (become pinker). And, the vagina should be moister (67).

Vitamin D may help to prevent and treat urinary tract infections and vaginosis. It helps to improve immunity in two ways. We have what is called an innate immune system and an adaptive immune system. The first one reacts to all threats (bacteria) in the same way, the second one responds to a threat (viral) it has faced before by adapting a specific response to it (68).  A lack of vitamin D is associated with reduced functioning of both types of immunity, so vitamin D may prevent, and helps to treat, urinary tract infections in this way.

It also helps protect against bacterial vaginal infections (BV or vaginosis). Here vitamin D regulates the production and function of antimicrobial defense molecules that protect the female body from invasive bacterial infection. This is important as up to 1 in 3 women may have such an infection at some point.  This is due to normal vaginal flora, good bacteria, being overtaken by bad bacteria.  Bacterial vaginosis is linked to increased risk of sexually transmitted disease, preterm deliveries and HIV infection (69). Other nutrient deficiencies linked to BV are zinc, vitamin A and iron. HPV is also linked to low zinc.   Low vitamin D contributes to cervical erosion as it may be necessary to form healthy cells.

Red light may improve libido. Red light treats hypothyroidism, which is known to cause low sex drive (81).  Further, a lack of adequate vitamin D levels (improved with light therapy) has been found to negatively affect sexual desire in women (70). This may partially be due to vitamin D’s effect on blood flow, including that in the sex organs. Here vitamin D receptors in blood vessels respond to the vitamin by being more elastic, by working better (71).  If your sex organs are not getting enough blood they will not work optimally.  Sex drive is also based in hormonal health.

If your reproductive hormones, necessary for sexual desire, are out of balance it can cause low libido or sex drive. Vitamin D is implicit in the production of testosterone and estrogen.  Women do make and need testosterone, if they lack it their sex drive goes down. Similarly, low estrogen can also affect desire (64).  Vitamin D is also needed for the nervous system to work properly, so a person can feel, get excited, and experience the sexual act to its upmost.  It is also needed for the production of neurotransmitters, those happy chemicals in the brain which create an organismic feeling 71 (71).  So, as well as affecting the desire to have sex, vitamin D deficiency can affect the ability to reach orgasm, sexual satisfaction overall, and sexual functioning in general.  Further, sexual pleasure may be impaired when the sex organs are painful due to vaginal dryness or cervical erosion. Both conditions are impacted by vitamin D deficiency.

Regarding PMS, lower levels of vitamin D circulating in a woman’s blood, (that which the body makes from the sun, food and supplements, called plasma 25-hydroxyvitamin D or 250 HD), is associated with PMS, with a higher risk of experiencing symptoms the greater the deficiency (59).  In this case vitamin D is associated with specific symptoms: breast tenderness, fatigue, depression, and swelling of feet and hands, bloating and intestinal problems (constipation or diarrhea).  This may be due to vitamin D influencing something called RAAS (the renin-angiotensin-aldosterone system) which, if not functioning properly in the female body, can lead to swelling or bloating of limbs, abdomen and sore breasts (59;60).  RAAS is also associated with fluid balance or retention, changes in blood pressure and possibly hypertension (59;75).  Regarding emotional problems, lower levels of vitamin D contribute to depression (59;76). Proper Vitamin D intake in women is associated with a lower risk of depression, uterine fibroids, fibromyalgia, and painful periods, called dysmenorrhea (59).

Further, vitamin D may be protective against cancer (breast, colon & prostate), insomnia, and an overactive immune system, as well as heart disease, renal disease, diabetes, and infections (84), as well as hypertension or raised blood pressure (60), as well as muscle weakness (46).

There are different types of vitamin D. Vitamin D3 (cholecalciferol) is the result of dietary intake and skin being exposed to UVB rays.  Vitamin D2 (ergocalciferol) is found only in a few foods, so supplements may be needed (84).  Sun exposure can produce a chemical reaction in the skin cells whereby the body converts ultraviolet B rays to vitamin D.

A fair skinned person only needs to be exposed to outdoor sun for about 10 minutes at midday (no sunscreen or sunglasses, ideally wearing shorts and a sleeveless top). A person of Hispanic origin, or who is tan, needs 15 to 20 minutes of similar exposure.  A person of African descent may need 6 times the exposure of a fair skinned person. Older adults, regardless of skin type, may need more sun as an aging body doesn’t make vitamin D as efficiently (84). Keep in mind that from November to March in northern latitudes there is insufficient UV rays to make enough vitamin D in the body (84).

Other options: foods high in vitamin D are fortified milk products, fortified cereals, high fat fish, fish oils, eggs, mushrooms, some juices, pastas and margarine’s (65).  Supplementation can be used to augment vitamin D from food and the sun (48).

Addictions: treatment is showing to be benefited by light therapy.  Red light has been used as part of the treatment protocol for alcoholism in humans and in opiate addiction in animal studies (29).  Dopamine or DA, which is released in the nucleus accumbens, or NAc, is known to be involved in addictions in that drugs can increase levels of DA in the NAc, while at the same time increasing the threshold at which the brain is stimulated to feel the reward of DA release in the NAc.  So, the brain becomes less excitable or able to produce this reward on its own, and more dependent on the drug and addictive behaviours set in.  If an addict stops using their drug of choice the level of DA in the NAc falls sharply, and a desire for the drug (and its ability to stimulate production of dopamine in the NA) is felt.  Red light stimulates the production of dopamine in the nucleus accumbens.

Blue light, which also stimulates dopamine production, has a greater impact on dopamine levels in healthy brains (no substances like alcohol) in comparison to red light, but red light can still stimulate the production of dopamine in the nucleus accumbens (area of brain) when the brain has alcohol in it (ethanol). In this way it may be used to ameliorate alcohol withdrawal (29).

Brain health, dementia prevention, mild traumatic brain injury, and Post Traumatic Stress Disorder: is improved by light therapy, specifically red to near infrared (NIR), in the wavelength range of 600 to 1,200 nm, has been shown in human and animal studies to improve brain health.  Keep in mind that the light must be strong enough to penetrate both the skin and skull bone and effect brain tissue. To do so a light must be able to penetrate 1 to 7 cm below the scalp’s surface. Clinically it has been shown that a 8-13 W multi-watt near infrared laser can do this. If you wanted to buy a light to help with cognitive health, you must get one with at least 15 W of power, which can reach 3 mm below the scalp’s surface (70). MedX Health in Toronto Canada produces a device, Model 1100 that is used clinically with humans (31). This device is FDA cleared in the US for home use.

These wavelengths of light can increase cellular metabolism of ATP, or adenosine triphosphate production, as the light wavelengths are absorbed by cytochrome c oxidase in the mitochondria. The light also increases early response genes, improves growth factor expression, modulates or increases production of both RNS (reactive nitrogen species) and ROS (reactive oxygen species). The latter are also known as free radicals, which can be helpful to immune functioning in small numbers, but cause health problems in large numbers.  Red/NIR activates the replication of mitochondrial DNA and encourages synaptogenesis (increase synapse connections between brain cells for better communication) and stimulates cell production (70).  In animal studies red light was shown to reduce the expression of what are called pro-apoptotic genes (gene meant to cause brain cell self-destruction), to increase expression of anti-apoptotic genes (meant to keep cells alive), and also increase the production of neurotrophic factors like nerve growth factor and BDNF or brain-derived neurotrophic factor (70), which are associated with neurogenesis and brain health. This effect of light therapy is associated with increased cortical function, decreased cognitive impairment, headache symptoms, anxiety, depression, and sleep disruption (70).  In a human trial of red/near infrared light on traumatic brain injury treatment was shown to increase regional blood flow within the brain (nitric oxide release improvement).  It also improved mitochondrial functioning more in damaged cells (hypoxic/compromised,) which promoted increased adenosine triphosphate or ATP, necessary for cells to produce energy (31). The study subjects showed improvement on cognitive functioning at one week, and at one and two months (31).

These individuals reported improvements in the following: sleep and PTSD symptoms. The participants significant others reported observed improvements in the following: better social, interpersonal, and occupational functioning.

In this way red light in the right spectrum is showing promise as a treatment for TBI or traumatic brain injury (70) as well as post traumatic stress disorder and as a way to protect against Alzheimer’s dementia and Parkinson’s disease. One human study of TBI showed participants had short term improvement on sustained attention, memory, and executive functions (70).  It was thought that the results were transitory because the light was not strong enough to properly reach the brain tissue it was targeting.  Another human study showed that after 18 sessions participants had improved attention, inhibition, and verbal memory (based on psychological testing).  TBI (3-20 years old) treated with a NIR multi-watt laser (power range of 8-13 W) with a minimum of 10 sessions (20 for some) has been proved to provide clinically significant results on irritability, anxiety, insomnia, and depression, as well as headaches and cognitive problems, including executive dysfunction and attention difficulties.  These subjects were all able to resume work and reported improvement on quality of life as well as symptoms either disappearing or becoming manageable.

In animal studies of stroke victims, the injury induced neurological deficits were reduced by 32% when light therapy was applied 24 hours after the injury occurred. Here neurones were shown to proliferate or grown and to migrate or have an affect on other brain areas (70).  Human trials have shown mixed results, depending on the strength of the light and the wavelengths being used.

In this way, Red light is showing promise as a way of increasing brain plasticity by stimulating the production of neurochemicals that increase the production of neurons and their connections (dendrites) serotonin (40) and BDNF (71;72).

Cognitive decline and brain shrinkage due to depression and stress: the hippocampus is known now to shrink in response to, prolonged, major depressive disorder (73). Some individuals experience up to a 20% loss in volume of this area, which has a pivotal part in memory and learning. The disruption of the functioning of the hippocampus in part explains the cognitive problems that are associated with depression. Stress is associated with hippocampus shrinkage. It causes the hippocampal neurons to retract regarding dendritic processes (this will revers when stress is no longer a problem). Stress inhibits (slows or blocks) neurogenesis in the mature (adult) hippocampus. Stress (if prolonged or sustained) causes a loss of pre-existing neurons in the hippocampus, called neurotoxicity (73). The glucocorticoid hormones (especially cortisol), which are produced during stress, are seen to be the reason for these changes to the hippocampus. The hippocampus has a considerable quantity of glucocorticoid receptors. Interestingly those with major depression often hypersecretion cortisol (about 50%). Cortisol disrupts production of the feel good and learning related neurotransmitter serotonin.

The hypothalamus is associated with depression. Specifically, the dysregulated of the HPA axis or the hypothalamic pituitary adrenal axis, as well as the hyperactivity of the subgenual cortex, the latter is associated with disrupted sleep patterns in those with depression or symptoms of depression. People who are not depressed have much stronger functional connectivity between the hypothalamus and the subgenual cortex. In people who are most depressed, the disruption in functioning is associated with increased cortisol secretion during deep sleep (74). It is believed that this is due to excessive production of cortisol during deep sleep, as well as a loose of functional connectivity between the hypothalamus and the subgenual cortex (Brodmann area or BA 32). The more sever the symptoms the  more cortisol was secreted (74).

Given that pharmaceuticals are known to treat only symptoms of emotional and cognitive problems, and that they are now being recognized as potentially impeding neurological regeneration (74), (depending on the drug), red light may be a good alternative treatment.

Post Traumatic Stress Disorder, or PTSD: may be treated with light therapy. In a small human trial comprised of four individuals who underwent 18 twenty-minute sessions, the subjects all showed a clinically meaningful decrease, or a reliable decrease, of symptoms on the PTSD measure PTSD Checklist – Civilian Version or PCL-C. Further, participants still showed this improvement two months post treatment.

When NIR or near infrared light is shined onto human skin (and into the brain) it increases the production of the protein cytochrome-c-oxy-dase. This protein is inside neurons, and it stimulates blood flow, this stimulation can last quite a while after the treatment ends. This is important as PTSD sufferers usually have less blood flow in the left side of the dorsal lateral prefrontal cortex. They can also lack the ability to pay attention.

Bright light therapy alone has been shown in studies with returning war veterans to help ameliorate PTSD related sleep disturbance, as well as to moderately improve depression and other symptoms of trauma. The participants received 10,000 lux of bright light, for 30 minutes a day, for four weeks. (39).

Sleep disturbance, reported as one of the most enduring and challenging symptoms, is highly problematic in PTSD, with traumatic events, in whole or part, being re-experienced in nightmares. Sleep related problems are reported by 70 to 90% of PTSD sufferers. So, it can not be overlooked in treatment design, as it can both precipitate and perpetuate the syndrome. It interacts with both anxiety and depression creating a vicious cycle. By simply improving a sufferer’s sleep quality, the severity of other symptoms can be reduced (39).

Red light for PTSD: Mechanism by which red light may help PTSD (31): is the same for the cognitive benefits regarding mild brain injury and reduced risk of dementia, as well as depression treatment, in that transcranial (across the cranial bone into the brain) red/NIR LED light results in an increase in ATP production within brain cells, a greater diffusion of nitric oxide which promotes the dilatation of blood vessels (vasodilation) and rCBF in cortical areas (or more oxygen moving through the brain’s arteries and veins), as well as decreased brain inflammation, and increased antioxidants. There also seems to be an increase in antioxidants within the brain and a corresponding decrease in inflammation.

Please not, this information is for educational purposes only. Please contact a qualified healthcare provider if you have any health, or other, issues.

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