Basic Seasonal Affective Disorder Causes are linked to reduced amount of daylight (sunlight) experienced during winter months in the extreme northern regions. Age, genetics and chemical imbalances in the brain triggered due to lack of sunlight during the day could be other causes for development of Seasonal Affective Disorder. Disturbance in the body sleep-wake cycle and changes in the levels of brain chemicals that affect the body cycle are believed to be the two main causes of SAD.
Different causes of Seasonal Affective Disorder
Circadian Rhythm Imbalance: Natural light (sunlight) stimulates certain functions in the human body. Light controls the circadian rhythm of the body and signals when it is bright daylight and when it dark hence regulating functions like sleep-wake cycle, energy, digestion, mood and appetite. When the circadian rhythm does not get proper cues from the body senses it tends to play up. This is because the body is unable to produce certain hormones like serotonin (regulates mood) and melatonin (regulates sleep-wake cycle).
Dim atmosphere leads to becoming unproductive and leaves feeling inactive. Therefore, people who suffer from SAD experience mood swings, lethargy, loss of energy and over sleepiness. The disturbed circadian rhythm clock leads to development of depressive behavior that causes SAD.
Serotonin Levels: Serotonin is a brain chemical that does the work of a neurotransmitter. It transmits brain signals to various parts of the body through nerve cells, particularly regulates mood and appetite functions in the body. When the body is incapable of converting serotonin chemical or serotonin polymorphisms into N-acetylserotonin with the assistance of serotonin N-acetyltransferase, SAD seasonal affective disorder symptoms develop. This happens because the serotonin being a neurotransmitter cannot transmit proper signals to the part of the body that promotes mood and carries out digestive procedures in the body.
It is believed that imbalance in serotonin levels may cause craving for sweet, starchy and fried foods and also could be the cause of indigestion issues. Growth of serotonin chemicals in the brain is related to the amount of natural light (sunlight). The exact process of production of compound that stimulates serotonin growth is yet to be studied. However, several studies have confirmed the effect of reduced sunlight on the production of serotonin.
Melatonin Levels: Melatonin is another chemical that is produced by the body in absence of sunlight. (That is when it is dark). Therefore, when light enters the eyes in the morning the body shuts down the production of melatonin. Hence, manufacture of melatonin is often more during winter months where sunlight is seldom seen. This affects the sleep cycle and mood of a person causing seasonal affective disorder. Research says melatonin is produced in the dark by the pineal gland in the body and is linked to the retina. The retina transforms the light signals into an electric impulse and transmits it to the hypothalamus in the brain. Then the hypothalamus sends signals to the pineal gland to produce less melatonin. The pineal gland is connected to the retina through the retinohypothalamic tract and suprachiasmatic nucleus. Hence, due to lack of light throughout the day the body tends to produce more melatonin that leads to difficulty in waking up in the morning and feeling of sleepiness during the day.
Other factors that cause SAD seasonal affective disorder are
• Psychological factors – strong emotions and instances that have left a mark on the mind of a person.
• Physical abuse and parental neglect during childhood
• Already persisting depression syndrome
• Genetic factors – family history of depression disorders
• Social factors – distressed relationship with friends, relatives and partner
Most of the SAD seasonal affective disorder causes are generic and psychosomatic in nature and hence can be treated easily. Self help treatment like exercise, proper diet and exposure to maximum amount of light in the day aids in curing SAD faster. Else, antidepressants or psychotherapy is successful in treating SAD.