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Some people are vulnerable to a type of depression that follows
a seasonal pattern. For them, the shortening days of late autumn
are the beginning of a type of clinical depression that can last
until spring. This condition is called “Seasonal Affective
Disorder," or SAD.
SAD is thought to relate to seasonal variations in light. A
“biological internal clock” in the brain regulates our circadian
(daily) rhythms. This biological clock responds to changes in
season, partly because of the differences in the length of the
day. For many thousands of years, the cycle of human life revolved
around the daily cycle of light and dark. We were alert when the
sun shone; we slept when our world was in darkness. The relatively
recent introduction of electricity has relieved us of the need to
be active mostly in the daylight hours. But our biological clocks
may still be telling our bodies to sleep as the days shorten. This
puts us out of step with our daily schedules, which no longer
change according to the seasons. Other research shows that
neurotransmitters, chemical messengers in the brain that help
regulate sleep, mood, and appetite, may be disturbed in SAD.
What are the Symptoms?
SAD can be difficult to diagnose. Generally, symptoms that
recur for at least 2 consecutive winters and may include:
- change in appetite, in particular a craving for sweet or
starchy foods
- weight gain
- decreased energy
- fatigue
- tendency to oversleep
- difficulty concentrating
- irritability
- avoidance of social situations
- feelings of anxiety and despair
Research in Ontario suggests that between 2% and 3% of the
general population may have SAD Another 15% have a less severe
experience described as the “winter blues." SAD tends to begin in
people over the age of 20 and is more common in women than in men.
Recent studies suggest that SAD is more common in northern
countries, where the winter day is shorter. Deprivation from
natural sources of light is also of particular concern for shift
workers and urban dwellers who may experience reduced levels of
exposure to daylight in their work environments. People with SAD
find that spending time in a southerly location brings them relief
from their symptoms.
Excerpts from CMHA National web site - SAD |
