Now that the longest days have gone and the dark mornings and evenings are lurking in the wings, it is time to think of seasonal affective disorder (appropriately SAD). This is a psychiatric disorder where autumn and winter depression alternate with spring and summer relief in the unfortunate sufferers.
Affective disorders are defined as those where mood is either a determinant or a main manifestation. Although strictly there are three affects concerned, namely anxiety, depression and elation, the first of these is usually given a place of its own, requiring special attention, while affective disorder is restricted to depression and elation. Since we tend to think of elation as a bonus over our common daily experience of life, it tends to be neglected in discussions of affective disorder, including seasonal affective disorder.
Depressive symptoms of the syndrome include fatigue, sadness, a tendency to oversleep and overeat with a craving for carbohydrates, social withdrawal (which makes it worse) and impaired productive capacity at work. Depression is attributed to oversecretion of melatonin, and light brings relief by inhibiting melatonin synthesis in the body. Treatment with visible light in the region of 2,500 lux brings dramatic relief of symptoms in nearly all SAD sufferers within a few days, but when illumination is discontinued the depression returns. Dosage with melatonin has been found to worsen depression, lower body temperature and slow reaction time. Antidepressants such as sertraline or fluoxetine are often effective in winter SAD, and psychotherapy has also been employed with success.
One symptom of SAD may be yawning, which is usually attributed to boredom, lack of oxygen or social example. This may be associated with changes from periods of high to low activity. Long sleepers ( 8 to 10 hours daily) tend to yawn more than short sleepers, with hormonal factors being held responsible. Yawning usually heralds an increase in physical or mental activity.
Little is known about the incidence of SAD in different individuals. It is considered to be less common in children and adolescents than in adults. Winter SAD in particular is apparently more troublesome in women than in men, but the depressive phase is claimed to be more severe in men than in women. There have been few reports of the effect in elderly people. Onset is generally between the ages of 20 and 30 years, but since many sufferers do not seek advice for several years, this is uncertain.
A serious disadvantage of light therapy is that it may cause headache and eye strain. Winter SAD responds well to treatment with sertraline or fluoxetine, but meclobemide is reported to be no more effective than a placebo. No harmful interaction between antidepressants and light therapy has been reported, and the two may be applied simultaneously.