Many find that the shorter days and longer nights this time of year affect their health. About 5 percent of the population develops seasonal depression, according to Mental Health America. Reduced amounts of daylight trigger the somewhat milder “winter blues” in another 10 to 20 percent, according to the American Academy of Family Physicians. Seasonal affective disorder, or SAD, affects women far more often than men; 4 out of 5 people with SAD are women. It also affects people under 30 more often than older people. Symptoms include typical signs of depression — such as low energy, sleep problems, changes in appetite and weight, and loss of interest in favorite activities. But with SAD, symptoms come and go with the season. No one knows what causes SAD, but most experts link its development to less exposure to the sun’s rays, brought about by shorter days in the fall and winter. This may disrupt your body’s internal clock, sparking depression, and reduce your body’s serotonin levels, increase melatonin levels and decrease vitamin D levels, affecting your mood. Treatment options include light therapy — sitting in front of a special light box for 20 to 60 minutes a day — as well as behavioral therapy and possibly antidepressants. If relocation is an option, consider heading south. The closer you are to the equator, the lower your risk for seasonal depression.