Causative & risk factors
The exact cause of SAD is unknown. It probably occurs due to lack of sunlight.
Lack of sunlight causes a disruption in levels of serotonin and melatonin. Both these hormones play a role in mood regulation. Some patients have a family history of SAD. Females are more commonly affected. People who live in areas with very little sunlight or extremely long summers are at a higher risk of developing seasonal affective disorder. People with SAD may have a history of other mental illnesses such as bipolar disorder, clinical depression etc.
Clinical presentation
Since the depression is seasonal, the symptoms usually begin in September/October and end in April/May. The patient experiences feelings of sadness or hopelessness. He loses interest in daily activities. He may become anxious or moody. Loss of energy and drowsiness may be present. The person tends to over eat high calorie foods leading to weight gain.
Patients experiencing depression during summer season experience loss of appetite and weight. They tend to sleep less, have a higher sex drive and are irritable.
If SAD is severe, the patient may even try to commit suicide or become addicted to drugs.
Investigations
The diagnosis of this condition is based on a thorough patient history.
Treatment
The patient is recommended to spend more time outdoors in sunlight whenever possible. Phototherapy (light therapy) is offered where the patient is made to sit in front of a box emitting bright light for half to one hour each day. The results are good but temporary. Psychotherapy and personal counseling is beneficial to the patient. Antidepressants drugs are given to the patient under medical supervision, after the possibility of bipolar disorder is eliminated.
