Every autumn, Louise finds her moods darkening, her energy waning, her sleep slipping away and her focus shattering. She craves carbohydrate-laden foods and she gains weight.

“It’s hard to get going,” says Louise of her symptoms. “It’s like you’re moving around in a big tank of water and there’s a pressure bearing down on you… everything becomes insurmountable.”

But when spring arrives, the 43-year-old paralegal and mother of two teens finds her energy and focus rebound.

Louise has Seasonal Affective Disorder (SAD), a mood disorder characterized by seasonal depression episodes. Symptoms include fatigue, lack of interest in typical activities, withdrawal from social contact, carbohydrate cravings and weight gain. The symptoms habitually appear in fall and winter and dissipate in spring and summer, although they may occur during the summer. Women are more at risk than men.

Scientists theorize the disorder is related to melatonin, a sleep-related hormone linked to depression. The brain makes more of the hormone in the dark so when daylight decreases, melatonin production increases.

Treatment options include spending time each day near a special bright fluorescent lamp, psychotherapy, melatonin supplements, antidepressant medication and daily exposure to, and exercise in, sunlight.

Louise takes antidepressant medication and schedules a daily dose of sunlight – at least a half hour in the morning and another during her lunch break at work – to relieve her symptoms.

“I spend as much time outside as I can,” Louise says. If you have symptoms similar to Louise’s, talk to your doctor about SAD and treatment options.