What is Seasonal Affective Disorder (SAD)

Definition: A mood disorder or form of depression related to a certain season of the year, especially winter, triggered by a decrease in exposure to sunlight. It develops in autumn or winter (between September and April, especially during Dec., Jan., and Feb.) and improves in spring and summer. SAD affects millions of people every winter and usually afflicts adults and is four times more common in women than men.

Symptoms include daytime drowsiness, fatigue, and diminished concentration:

• a desire to oversleep and difficulty staying awake, but in some cases, disturbed sleep and early morning wakening;
• feeling fatigued and an inability to carry out normal routine;
• a craving for carbohydrates and sweet food, usually resulting in weight gain;
• feelings of misery, guilt, and loss of self-esteem, sometimes hopelessness and despair, sometimes apathy and loss of feelings;
• an irritability and desire to avoid social contact;
• a tension and inability to tolerate stress;
• a decreased interest in sex and physical contact;
• And in some sufferers, extremes of mood and short periods of hypomania (over activity) in spring and autumn.

Main Cause: SAD is related to the secretion of the hormone melatonin, a sleep-related hormone secreted by the pineal gland in the brain. This hormone is believed to cause symptoms of depression and is produced at increased levels in the dark. So when the days are shorter and darker, the production of this hormone increases. In animals, fluctuation of melatonin is responsible, in part, for seasonal cycles, such as hibernation. Other neurotransmitters, or chemical messengers in the brain, including serotonin and dopamine, have been linked to SAD, as well.

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