NEW YORK (PIX11) – The sun will be setting a lot earlier through March after the clocks were set back by an hour on Sunday.

Less sunlight and shorter days can trigger seasonal affective disorder, which affects an estimated 10 million people.

Dr. Kimberly Kleinman, a senior psychologist at New York Presbyterian, explains the difference between S.A.D. and what’s commonly referred to as “the winter blues.”

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