Encyclopedia of Health and Medicine

S–T
seasonal affective disorder (SAD) DEPRESSION
that develops during the winter months when the
hours of darkness exceed the hours of daylight.
Researchers believe a key factor in SAD is an
increase in the amount of MELATONIN the PITUITARY
GLAND produces. Melatonin is a HORMONE that regulates
the body’s circadian cycle (wake and sleep
pattern). Darkness stimulates melatonin release.
Higher than normal levels of melatonin cause
tiredness and reduce energy. Bright light causes
the pituitary gland to back off melatonin production,
causing wakefulness and alertness. Another
factor may be the level of serotonin, a NEUROTRANS-
MITTER associated with mood, in the BRAIN.
Symptoms of SAD commonly appear each year
during the winter months and include
• profound lethargy
• disinterest in life
• tiredness or urge to sleep
• craving for sweets (simple carbohydrates)
• weight gain
See also EXERCISE AND HEALTH RISK REDUCTION;
POSTPARTUM DEPRESSION; SLEEP DISORDERS; WALKING
FOR FITNESS; WEIGHT LOSS AND WEIGHT MANAGEMENT.
schizophrenia A serious psychotic disorder with
marked emotional, cognitive, and physical symptoms.
Schizophrenia represents a profound and
disabling break from reality. Researchers do not
know what causes schizophrenia, though it tends
to run in families, which suggests a genetic foundation
is likely. Differences in BRAIN structure in
people who have schizophrenia, apparent with
diagnostic imaging, also suggest organic factors
that likely affect the ways the brain receives,
organizes, and processes information. Symptoms
in men often begin in late ADOLESCENCE or early
adulthood; symptoms in women tend to develop
in early to middle adulthood. More than three
million Americans have schizophrenia.
Symptoms and Diagnostic Path
There are five types of schizophrenia—catatonic,
disorganized, paranoid, undifferentiated, and
residual—that share many common symptoms as
The most effective treatment for SAD is exposure
to bright light, ideally sunlight outdoors.
Walking an hour a day in the winter often dramatically
improves symptoms, likely a combination
effect of the exposure to light and exercise.
Arranging one’s workspace to have as much natural
well as have unique symptoms. These symptoms
must be continuous six months or longer and represent
a dramatic and observable deterioration
in function. Symptoms common to all types of
schizophrenia, though present to differing degrees
in different types, include
light as possible (or using light bulbs that emu-
late daylight) is often helpful for people who
cannot get outdoors during daylight hours. Symptoms
cause significant enough dysfunction in
•
•
DELUSION (untrue belief)
HALLUCINATION (false sensory perception)
some people to warrant therapy with ANTIDEPRES-
• chaotic or disordered thought processes and
SANT MEDICATIONS, typically selective serotonin expression of ideas
reuptake inhibitors (SSRIs) to increase serotonin
levels in the brain.
• bizarre behavior and involuntary movement
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