New Delhi, Nov. 9 -- Shorter days and longer nights can bring more than a temporary dip in mood. For people with seasonal affective disorder, the change in seasons can trigger depression that disrupts sleep, drains energy and makes everyday activities difficult for months.

recurring winter depression is not something people simply have to endure.

More than a dislike of winter

Seasonal affective disorder, often shortened to SAD, is depression with a recurring seasonal pattern. According to the National Institute of Mental Health, winter-pattern symptoms usually begin in late autumn or early winter and ease during spring and summer. Episodes can last about four to five months.

Symptoms can include persistent sadness, loss of interest in...