Seasonal Affective Disorder, or SAD, was first described and named by the South African psychiatrist Norman Rosenthal in 1984.

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Those head doctors, they have a term for the effect a lack of sunshine has on your physiology: SAD, or seasonal affective disorder.

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Light is used to treat medical conditions including seasonal affective disorder a cyclical depression often tied to low sunlight as well as skin, eye and gastrointestinal conditions.

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Helen Hanson has lived with seasonal affective disorder for 20 years.

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The title of my first column is Seasonal Affective Disorder.

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The University of Kansas study suggests a sharp drop-off in the amount of daylight in New York in September might trigger seasonal affective disorder and make some traders more risk-averse.

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And finally, those who suffer from seasonal affective disorder (SAD) or other mental health conditions can find the darkness of winter especially difficult, making them less productive and interested in work.

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