Seasonal Affective Disorder


Seasonal Affective Disorder, or SAD, is a common problem of people
living in northern United States. People who are affected by this disorder
commonly suffer from depression, lethargy, inability to concentrate, overeating
and weight gain. People from the north tend to suffer more from this disorder
because of the shortened days. It appears, that due to the deficiency of
sunlight some people suffer from these symptoms. The shortened days have a
hormonal effect on the body that causes these symptoms, and the use of
artificial sunlight is the best way to relieve the disorder.
It was not until recently that SAD was discovered. It was discovered by
Peter Mueller, who was reviewing a case of a 29-year-old woman. He had noticed
a pattern, the woman’s depression came in the winters and left in the spring.
Over the course of years the woman moved from city to city. Mueller noticed,
that the farther north she moved the early the depression. Mueller had begun to
speculate that the lack of sunlight had contributed to the women’s depression.
In order to confirm this he exposed the patient to artificial sunlight. He
found that over a period of time the patient had recovered from the depression.
Today light therapy is the most commonly used method in treating SAD.
The two hormones that are affected by the sunlight, and are thought to be
the cause of SAD, are melatonin and serotonin. Both of these chemicals “are
influenced by photoperiodism, the earth’s daily dark-light cycle” (Wurtman 1989).
Melatonin is the chemical that effects mood and energy levels. In the human
body melatonin is at its highest at night and is lowest in the day. There has
been a study done to see if sunlight has a direct effect on suppressing
melatonin. It is known that melatonin levels in urine are five times higher at
night than they are in the day. It was not until a 1980 study that it was known
that melatonin levels could be directly suppressed with light. In an experiment,
subjects were woken up at two in the morning and exposed to a half an hour of
artificial sunlight. The findings were that melatonin levels were greatly
decreased. The decline in melatonin usually happens in the early morning, but
in a SAD patient this does not occur until about two hours later. In order to
suppress the levels the patient needs to be exposed to sunlight. It is found,
that when the patient is exposed to the light there is a significant decrease in
depression and the craving for carbohydrates. It is not known if SAD is
directly caused by melatonin. We are still not sure what is the direct cause
for the depression of SAD. We do know why people who suffer from SAD crave
carbohydrates.
Serotonin is the chemical that regulates a person\'s appetite for
carbohydrate rich foods. A patient who suffers from SAD, and is given an
artificial shot of serotonin called d-fenfluramine “leads to a decrease in
stress-induced eating” (Scientific American 1986). In each person blood stream
we have a hormone known as trypton that is a derivative of serotonin. When it
enters the central nervous system and reaches a group of cells called raphe
nucli it is converted into serotonin. The amount of trypton in the blood is
increased when carbohydrates are consumed. This may explain why many people who
suffer from SAD have an increase their intake of carbohydrates. In testing
results it patients who suffer from SAD when given “an 800-calorie, high-
carbohydrate meal (six cookies), they reported feeling vigorous and energized”
(Health 1989).
A large consumption of carbohydrates is one of the symptoms of SAD. In
a number of cases, it has been noted that in the fall a person suffering from
SAD will increase their intake of carbohydrates and decrease in the summer. It
is also found, that those who crave carbohydrates tend to consume most of them
in the late afternoon or early evening. A carbohydrate craver is found to eat
1,940 calories at a mealtime. The average for an adult female is 1,500 to 2,00
calories, an adult male from 2,200 to 2,700 calories. It is in the early
evening that the craver consumes “an additional 800 or more calories person per
day” (Wurtman 1989). The increase of carbohydrates leads to an increase in the
levels of serotonin that relieves the symptoms of SAD.
The evidence all seems to push towards lack of daylight as the reason
for SAD. Little research, although, has been done on the effects of temperature
and barometric pressure on mental health. These factors change during different
times