Sunny side up

Dr. David Mischoulon studies how seasonal changes affect mental health. (Travis Dove for the Boston Globe)

Look for the start of Daylight Savings Time this Sunday to add more than just an extra hour to the day. Dr. David Mischoulon, a specialist in seasonal affective disorder, says the additional sunlight exposure for our bodies also means potential cheerfulness for our souls. People with even mild cases of seasonal affective disorder may feel a positive difference after this weekend, says Mischoulon, of the MGH Depression Clinical and Research Program. Here, in edited and condensed form, is what he had to say on the issue last week. - PATRICIA WEN

Q. Is seasonal affective disorder just a fancy name for the "winter blues"?

A. Not at all. People with a serious case of this disorder suffer a seasonal-related depression - starting in the fall, they can experience an overall depressed mood, sleep disturbances, appetite changes (including an increased craving for carbohydrates), poor concentration, social withdrawal, among other symptoms. Many require antidepressants, light therapy, or cognitive behavioral therapy to bring them out of the human equivalent of a hibernating mode.

Q. Hibernating? Please explain.

A. Like bears and frogs, we're genetically wired to slow down in the winter. Hibernating animals are affected by the shorter days of winter: fewer photons hit the retinas of their eyes, changing the circadian rhythms and triggering long periods of sleep. Some people are vulnerable to these hibernation patterns, leading to daytime sluggishness in the winter - and in severe cases, a full-blown depression.

Q. What is a moderate or mild sufferer to do?

A. Light therapy can help. You can buy these special lights and sit under them for a half-hour, twice a day. That has proven effective for many people. Engaging in more outdoor daytime activities to increase natural light exposure or setting up an exercise routine can also help. Some alternative remedies, such as acupuncture and herbal supplements, show promise. We're also looking into research on whether changing a person's diet - such as adding carbohydrates that can be derived from potatoes - may help serotonin synthesis and help regulate moods at any time of the year.

Q. Is this an upcoming headline: Eating french fries reduces depression?

A. No. While the carbohydrates we studied are derived from potatoes, that doesn't mean that there's a direct connection between eating potatoes and mood improvement. We use a concentrated, purified form of these carbohydrates. Our results are very preliminary.

Q. Do you empathize with sufferers of seasonal affective disorder?

A. A lot of healthy people will have a drop in their mood during the winter. When I spend a week in a warm place during the winter, such as a vacation or a medical conference in Florida, I'm definitely in a better mood - and the benefits go beyond the length of the time that I'm away.