A year or two after my experience, Dr Nathan Rosenthal of South Africa moved to New York, where he experienced the same kind of mood change I went through. He also noticed his depression lifted when spring arrived. Not long after, at the NIMH, he met Herb Kern, who had been through a similar experience. Rosenthal began exposing Kern to light, and almost immediately noticed a marked improvement in his mood. People with SAD often experience symptoms associated with atypical depression, including increased sleep, increased appetite and carbohydrate craving, weight gain, irritability, interpersonal difficulties and heaviness in the legs and arms.
Women are four times more likely to be affected than men.
People with a long history of depression or bipolar need to be especially mindful of the change in seasons, many who await the turning of the leaves with a trepidation that borders on terror. SAD is most likely to affect people in higher latitudes and coincides with the darkest months of the year, making the seasonal reduction in light the obvious culprit. But how this registers on the brain is still a matter of speculation. One theory is that serotonin levels drop off in winter. Another is that melatonin secretion may be the cause.