Seasonal Affective Disorder, Light Therapy

I have been interested in learning more about Seasonal Affective Disorder and the different light therapies. Being that we are in Victoria, BC, and our winter months consist often of 'grayness', without the reflection of the sun on the snow to brighten the day or blue skies for days at a time, our climate does suggest that the prevalence of S.A.D. should be high.  Here we will describe what is SAD and discuss the different light therapies and all of their uses.

Seasonal Affective Disorder (SAD)

What is SAD?

SAD is a type of depression characterized by the period of the year. It starts late autumn and lasts till the sun gets stronger in the sky in the late winter into spring. SAD can range from being similar to dysthymia which is a low dark or sad mood that is sustained for at least 2 years to a major depressive disorder, which is characterized by the feelings of sadness, loss, anger, or frustration and it interfere with everyday life for weeks at a time or longer. The obvious increase in appetite and sleep, decreased energy levels and ability to concentrate, loss of interest in normal activities and social withdrawal are also a part of depression. There is also Subsyndromal seasonal affective disorder (SSAD) which is a milder version experienced by 14% of the US population.



The cause of SAD or depression is not fully known. There are most likely genetic, biologic and environmental factors at play. Family history, serotonin neurotransmitters (major player) acetylcholine and catecholamines ( like : dopamine, norepinephrine and epinephrine)  from the corticotrophin releasing factor (CRF) and the pineal gland who release melatonin (produced in darkness), all of these are involved at different stages of hormone release in the body and whether they are released too quick or too slow will have a major effect on a persons level of function. Also different prescription drugs could have side affects on the brain chemistry such as: drugs for acne, contraception, inflammation, gastrointestinal relief, high blood pressure, are a few of the common effectors

Good sleep, exercise and eating habits, socializing and avoiding addicting substances will help decrease SAD. An early detection and awareness of the problem can reduce the progression, also talking to your doctor are all great choices to make when faced with depression.


Light Therapy

There are two forms of phototherapy, non-targeted phototherapy and targeted phototherapy.

Targeted phototherapy.

For psoriasis the targeted phototherapy focus UVA (315-400nanometers (nm)) 1-2 minutes &UVB (280-315nm) 5-15 minutes both are applied to a specific skin region, longer exposure than the prescribed time will result in burns. The psoria-light is the only one that has been approved in Canada to provide UVA and UVB in the same light. 

light at 415-430nm produces visible violet light that is antibacterial, thus can treat acne, 80% of the time within 3 months, 10% do not improve. Treatment is safe except with people with porphyria and eye protection must be worn to protect the retina.

Ultraviolet light therapy therapy has been proven to be effective in treating cutaneous T-cell lymphoma, including mycosis fungoid.

Most common treatment for other skin condition is UVB at 311 to 313 nm.

Non-targeted phototherapy

Light boxes are non-targeted phototherapy which are used for circadian rhythm sleep disorders and SAD they filter out most UV waves. Side effects can be eyestrain, headache and mania. People who take drugs that increase their sensitivity to light, such as certain psoriasis drugs, antibiotics, or antipsychotics, should avoid light therapy.

Most people report feeling better after using a light box, it is thought* that the therapy fills the need to sun exposure. Mayo Clinic states that light therapy is proven for treating seasonal affective

disorder. In another study light treatment shows earlier response onset, lower rate of some adverse events, and no other significant differences in outcome between light therapy and antidepressant medication. An alternate solution to a light box is a heliostat where you reflect the sunshine from the outdoors into your face with a mirror... the only problem in Victoria it the  lack of blue sky and sun emerging. 

For non- seasonal depression it is thought* that light therapy is a promising avenue, but needs more research *.

Looking at a light make sure you follow these guide lines, since the product is not main stream and heavily studied.

"Our recommendations are based on the following principles:

1) the light device should be tested and found effective in scientifically valid studies,

2) the light device should have a filter that blocks harmful ultraviolet rays,

3) the light device should be CSA approved if used in Canada (UL approved in the US), and

4) the light device company should have a track record of reliability. 

We recommend fluorescent light boxes because they have been extensively tested with the greatest evidence for effectiveness in scientific studies, and we have experience with these devices. Other light devices, for example, light emitting diode (LED) devices, light visors and dawn simulators, may be beneficial for some patients but there is less evidence for effectiveness compared to light boxes.  Most light devices use white light. We do NOT recommend narrow-band blue-light devices because they have not been extensively tested, there is no indication that blue light is better than white light for SAD, and there is no information on long term safety " link  

There are so many more studies to read and information from different countries to analyze. I hope this summary is a starting ground to understanding the extent of light therapy and the learning curves that comes with it.

Hopefully after more research and classes Equinox Health Clinic will be offering Vitamin D light therapy and SAD light therapy.

Here is another great article to leave you on.    

Equinox Health Clinic

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