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How exactly does Light Therapy work?

Hello and Welcome. It is spring for those of us living in North America. Winter conditions attempt to hold on for one last breath, because it knows time has come for it to retreat...for awhile; thank goodness! Even as spring gives way into summer and management of SAD symptoms ebbs, it is still very helpful to continue to take care of your symptoms through the interim. So, let's get to the content for the question above. I thought I would begin with three main biological facts that point towards the purpose of Light Therapy. We all share this common ground whether we suffer or not from Seasonal Depression. And, it is amazing to understand how the human body is designed and how it functions:

  1. Melatonin - It is a hormone produced by a gland the size of a pea located under the brain, called the Pineal Gland. During the night, this gland releases melatonin into the bloodstream in tiny quantities and continues to do so until dawn. It assists with our ability to get a good nights sleep.

  2. Serotonin, Dopamine and Norepinephrine - These are three neurotransmitters that "communicate" with neurons via receptors specific to the particular neurotransmitter, one of the three above. To clarify each: Serotonin is complex, so to focus on the subject at hand, it acts as a mood stabilizer and helps to produce healthy sleeping patterns. It helps us to "feel" good. Dopamine allows us to feel pleasure and enjoy human experiences. Easy enough to understand it's function. Norepinephrine's role in the sleep-wake cycle helps you to wake up, in increasing attention and focusing on performing a task.

  3. Circadian Rhythm - Also referred to as biorhythm or sleep/wake cycle; this is one's internal clock that runs constantly, cycling between alertness and sleepiness. The circadian rhythm helps regulate sleep patterns. The gland that regulates this rhythm is the pineal gland that synthesizes and secretes Melatonin.

These three biological functions are the trifecta; working together to insure our bodies get rest when needed, experience feelings of joy and have energy to focus for the next 24 hours. Understanding what is supposed to occur, to live each day to the fullest, provides the bench mark to help us gauge how close or far off we are in our own quality of life in 24 hours.


Studies have shown that the portion of the brain (hypothalamus) responsible for functions like eating, sleeping and biological rhythms, levels of the neurotransmitter, Serotonin, drop tremendously during winter. This finding set the tone that seasonal changes in Serotonin may be a trigger for SAD. Using Light Therapy helps to influence the response in the brain and boost serotonin transmission. In addition, the neurotransmitter dopamine may go awry in those with SAD, according to Dr. Rosenthal in his book mentioned previously: Winter Blues. He also says that temperature regulation and ocular function depend on dopamine. Light therapy works to boost one's mood by increasing dopamine release. Interestingly, dopamine levels in the retina would affect the circadian rhythm positively, thus improving sleep patterns. Lastly, evidence has shown that Melatonin is under direct influence of the neurotransmitter, Norepinephrine. For people with SAD, the duration of melatonin secretion expands at night. And, Light therapy would help to decrease the secretion of Melatonin. These systems, being affected through the use of light therapy, have a chance to regulate and restore normal daily circadian rhythm function.


To sum things up, Light Therapy works to counteract the affects of SAD, but the practical application of Light Therapy deserves a post specific to that. And this is intended to be a 2 minute blog post. I'll dive into that next week.


I hope this information gives you an insight to how this type of therapy works and that if you believe it can be of help to you now or during the next season of your Seasonality (which most surely will return), I encourage you to see a practitioner for diagnosis and guidance.


Until next week, it's OK to be SAD...just don't stay there. Thank you for letting me share with you today. Jeanine




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