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Seasonal Affective Disorder

Hormones, Neurotransmitters and SAD

    © 2016

Biologicial--Biochemical Abnormalities

Hormones and Neurotransmitters

     Specific brain chemicals and neural pathways are responsible for regulating mood and related behaviors.  The pineal gland (an endocrine gland) helps accomplished this function by producing several important hormones including melatonin and serotonin.  As daylight hours shorten during the winter months, melatonin and serotonin production is affected, and this may affect mood and sleep patterns. 
     During the winter,  with shorter daylight hours and longer nighttime hours, the secretion of




become unbalanced.  Sunlight triggers serotonin, and the quantities decrease, as the daylight hours become shorter. Darkness triggers melatonin production, and the chemical is secreted in larger quantities as the nighttime hours become longer.  This causes a chemical imbalance and a decreased ability to battle SAD.  When spring returns and daylight increases, people with SAD experience relief from their symptoms, and return to their usual mood and energy level.

     Experts do not fully understand why SAD affects some people more than SAD affects others.  Some people may be more sensitive to variations in light, and this may cause significant changes in hormone production.  Other genetic variables, e.g., a photopigment gene in the eye, may play a role in causing SAD.

What happens during the winter months?

Pineal Gland

Treatment for SAD

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     Melatonin is a hormone that has many purposes including being part of the system that regulates the circadian rhythm. 


(the precursor to melatonin) is a neurotransmitter that regulates mood, appetite and cognitive functions.  Serotonin and melatonin have opposite functions with serotonin stimulating us during the day and melatonin inducing sleep at night.