often affects people's moods. Sunlight breaking through
clouds can lift our spirits, while a dull, rainy day may
make us feel a little gloomy. While noticeable, these shifts
in mood generally do not affect our ability to cope with
daily life. Some people, however, 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.
form of SAD, often referred to as the "winter blues," causes
discomfort, but is not incapacitating. However, the term
winter blues can be misleading; some people have a rarer
form of SAD which is summer depression. This condition
usually begins in late spring or early summer.
of this mental condition has existed for more than 150
years, but it was only recognized as a disorder in the early
1980s. Many people with SAD may not be aware that it exists
or that help is available.
be a debilitating condition, preventing sufferers from
functioning normally. It may affect their personal and
professional lives, and seriously limit their potential. It
is important to learn about the symptoms, and to know that
there is treatment to help people with SAD live a productive
into the causes of SAD is ongoing. As yet, there is no
confirmed cause. However, SAD is thought to be related 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.
are the Symptoms?
be difficult to diagnose, since many of the symptoms are
similar to those of other types of depression or bipolar
disorder. Even physical conditions, such as thyroid
problems, can look like depression. Generally, symptoms that
recur for at least 2 consecutive winters, without any other
explanation for the changes in mood and behaviour, indicate
the presence of SAD. They may include:
change in appetite, in particular a craving for
sweet or starchy foods
tendency to oversleep
avoidance of social situations
feelings of anxiety and despair
symptoms of SAD generally disappear when spring arrives. For
some people, this happens suddenly with a short time of
heightened activity. For others, the effects of SAD
of summer depression may include:
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."
affect some children and teenagers, but it tends to begin in
people over the age of 20. The risk of SAD decreases with
age. The condition is more common in women than in men.
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.
with SAD find that spending time in a southerly location
brings them relief from their symptoms.
feel depressed for long periods during autumn and winter, if
your sleep and appetite patterns change dramatically and you
find yourself thinking about suicide, you should seek
professional help, for example, from your family doctor.
There is effective treatment for SAD. Even people with
severe symptoms can get rapid relief once they begin
with mild symptoms can benefit from spending more time
outdoors during the day and by arranging their environments
so that they receive maximum sunlight. Trim tree branches
that block light, for example, and keep curtains open during
the day. Move furniture so that you sit near a window.
Installing skylights and adding lamps can also help.
relieves stress, builds energy and increases your mental and
physical well-being. Build physical activity into your
lifestyle before SAD symptoms take hold. If you exercise
indoors, position yourself near a window. Make a habit of
taking a daily noon-hour walk. The activity and increased
exposure to natural light can raise your spirits.
vacation in a sunny destination can also temporarily relieve
SAD symptoms, although symptoms usually recur after return
home. At home, work at resisting the carbohydrate and sleep
cravings that come with SAD.
people with SAD respond well to exposure to bright,
artificial light. "Light therapy," involves sitting beside a
special fluorescent light box for several minutes a day. A
health care professional should be consulted before
beginning light therapy.
people who are more severely affected by SAD, antidepressant
medications are safe and effective in relieving symptoms.
Counseling and therapy, especially short-term treatments
such as cognitive-behavioral therapy, may also be helpful
for winter depression.
Increasing your exposure to light, monitoring your diet,
sleep patterns and exercise levels are important first
steps. For those who are severely affected, devising a
treatment plan with a health care professional consisting
of light therapy, medication and cognitive-behavioral
therapy may also be needed.
What treatments are available for SAD?
has shown that many patients with SAD improve with exposure
to bright, artificial light, called light therapy, or
phototherapy. As little as 30 minutes per day of sitting
under a special fluorescent light box results in significant
improvement in 60% to 70% of SAD patients.
How does light therapy work?
know, exactly, but research shows that light has a
biological effect on brain chemical (neurotransmitters) and
function. One theory is that people with SAD have a
disturbance in the biological clock in the brain that
regulates hormones, sleep and mood, so that this clock runs
slow in the winter. The bright light may help to reset the
clock and restore normal function. Other theories are that
neurotransmitter functions, particularly serotonin and
dopamine, are disturbed in SAD, and that these
neurotransmitter imbalances are corrected by light therapy
and/or antidepressant medications. Still other scientists
believe that patients with SAD have reduced retinal light
sensitivity in the winter that is corrected by light
therapy. There is also evidence for a genetic basis for SAD.
How do you use light therapy?
fluorescent light box is the best-studied light therapy
treatment. Patients usually purchase a lightbox and use it
in their own homes. The usual "dose" of light is 10,000 lux,
where lux is a measurement of light intensity. Indoor light
is usually less than 400 lux; a cloudy day about 3,000 lux;
and a sunny day is 50,000 lux or more. Using the light box
for about 30 minutes a day is usually enough for a
How do I get a lightbox?
portable lightboxes are now commercially available. Ask your
doctor, or contact our clinic for more information. The cost
of a lightbox is usually between $200 and $400. We do not
recommend building your own lightbox, because of the safety
hazards, and the difficulty in getting the correct dose of
Are there side effects to light therapy?
effects of light therapy are usually mild. Some people may
experience nausea, headaches, eye strain, or feeling edgy
when they first start using the lightbox. These effects
usually get better with time.
no known long-term harmful effects of light therapy.
However, people with certain medical conditions (such as
retinal disease or diabetes) or taking certain medications
should have special eye examinations before considering
Are there other treatments for SAD?
treatments for depression, including the newer
antidepressant medications (e.g., selective serotonin
reuptake inhibitors, or SSRIs) are also effective for
patients with SAD. Counselling may also help. People with
milder symptoms of the winter blahs may be helped by simply
spending more time outdoors and exercising regularly in the
winter (e.g., a daily noon hour walk).
To Go For More Information
further information about seasonal affective disorder,
contact a community organization to find out about support
and resources in your community.
Canadian Mental Health
UBC site on Seasonal Affective Disorder.