Seasonal affective disorder, or seasonal mood disorder, is a type of depression that typically occurs in the fall and winter months. The National Alliance on Mental Illness reports that seasonal affective disorder often starts in the patient's 20s, most cases are women and 55 percent of patients report having a relative with some type of depression. Symptoms include fatigue during the day, carbohydrate craving, decreased interest in sexual activity and hopelessness. The National Library of Medicine lists the most common treatment for seasonal affective disorder as phototherapy. The exact cause of the disorder is not known.
Disrupted Biological Clock
The biological clock, or circadian rhythm, is responsible for regulating the sleep-awake cycle and other physiological processes in the body. The clock functions in response to light. When there is less sunlight in the fall and winter months, or even on cloudy days during other seasons, the biological clock may become disrupted. This can result in mood changes and feelings of depression. Phototherapy, also known as light therapy, is typically the treatment of choice to manage these symptoms.
Unbalanced Melatonin
Decreased exposure sunlight can disrupt the levels of melatonin in the body, the Mayo Clinic explains. Melatonin is a hormone produced by the body that helps regulate sleep and mood. If melatonin levels become unbalanced, feelings of depression and tiredness can result. In some cases, melatonin supplements can provide relief of symptoms. Consult with your physician to determine if a supplement would be effective.
Decreased Serotonin
Similar to other types of depression, seasonal affective disorder may be caused by decreases in the level of serotonin in the brain. Serotonin is a chemical that regulates mood. The Mayo Clinic explains that serotonin levels respond to light. This means that during colder months when there is less daylight, serotonin levels can decrease, causing tiredness, hopelessness and other depressive symptoms. Phototherapy, in addition to anti-depressive medication, may be prescribed to increase serotonin.
