With the days getting shorter and the winter solstice quickly approaching, we tapped into the medical expertise of Elsevier Author, Meir Kryger, MD, to gain some insight on  Seasonal Affective Disorder (SAD), a condition that affects up to 10% to 20% of the population. Dr. Kryger is a professor of medicine at the Yale School of Medicine and editor of several leading books on sleep medicine, including the core text in the field, Principles and Practice of Sleep Medicine.

Throughout the winter months, many people will suffer recurrent episodes consistent with SAD mood swings, which includes low energy, irritability, weight gain, and overeating. According to Dr. Kryger, climate, genetic vulnerability, and sociocultural factors all play a role in this very real mood disorder.

“Seasonal Affective Disorder is a mood disturbance, but unlike typical symptoms of major depression, patients often experience increased appetite for carbohydrates, weight gain, and increased sleep duration,” Kryger says.

Symptoms of SAD often recur annually but people who are affected should not be without hope. Treatments such as phototherapy and timed light exposure can be used to prevent the biologic changes that mediate SAD, such as increased levels of melatonin.

“Timed light exposure can help shift the body’s circadian system to treat both sleep phase and depressive disorders. In winter depression, the optimal timing of light therapy must be specified relative to the patient’s circadian clock rather than solar time. Light exposure is more effective than placebo treatment when light is administered in the evening or in the morning. However, it appears that morning exposure is more effective than evening exposure,” adds Dr. Kryger.

Read more about Dr. Meir Kryger and his textbook by visiting Dr. Kryger’s Elsevier Authors page. To read the full article on SAD, visit Reuters.