This is the VOA Special English SCIENCE REPORT.
Some people feel sad or depressed during the winter months in northern areas of the world. They may have trouble eating or sleeping. They suffer from a condition known as Seasonal Affective Disorder, or S-A-D.
Victims of S-A-D suffer its effects during the short, dark days of winter. The problems are most severe in the months when there are fewer hours of daylight. When spring arrives, these signs disappear and S-A-D victims feel well again.
The National Mental Health Association reports that S-A-D can affect anyone. The group says young people and women are at the highest risk for the disorder. It says that an estimated twenty-five percent of the American population suffers from some form of S-A-D. About five percent suffer from a severe form of the disorder. Many people in other parts of the world also have the condition.
For example, some scientists who work in Antarctica suffer from Seasonal Affective Disorder. During the long, dark winter months there, workers have difficulty finding enough energy to do their jobs.
The idea of health problems linked to a lack of light is not new. Scientists have discussed the issue since the beginning of medicine. More than two-thousand years ago, the Greek doctor Hippocrates noted that the seasons affect human emotions.
Today, experts do not fully understand S-A-D. Yet they agree that it is a very real disorder. Many doctors think that a change in brain chemistry causes people to develop S-A-D. They say people with the condition have too much of the hormone melatonin in their bodies.
The pineal gland in the brain produces melatonin while we sleep. This hormone is believed to cause signs of depression. Melatonin is produced at increased levels in the dark. So, its production increases when the days are shorter and darker.
To treat the disorder, victims of S-A-D do not need to wait until spring. Experts know that placing affected individuals in bright light each day eases the condition. There are other things people can do to ease the problem. They can increase the sunlight in their homes and workplaces. They can spend more time outdoors in the fresh air during the day.
One study found that walking for an hour in winter sunlight was as effective as spending two-and-one-half hours under bright light indoors.
This VOA Special English SCIENCE REPORT was written by George Grow.