seasonal affective disorder


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Related to seasonal affective disorder: Light therapy

seasonal affective disorder

(SAD), recurrent fall or winter depression characterized by excessive sleeping, social withdrawal, depression, overeating, and pronounced weight gain. SAD effects an estimated 6% of Americans; for reasons not yet understood, 80% of those affected are women. Most children who are affected have a close relative who also has SAD or another psychiatric condition. The disorder particularly affects people who live in the upper latitudes.

Although the mechanism of the disorder is not perfectly understood, it is known to be a reaction to the biological effects of light on the body (see biorhythmbiorhythm
or biological rhythm,
cyclic pattern of changes in physiology or in activity of living organisms, often synchronized with daily, monthly, or yearly environmental changes.
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). Daily, or circadian, rhythms help animals keep track of the seasonal changes in the environment, such as the shortening of days in winter, so that they can make the adaptive changes necessary for their survival in each season. Two substances, the hormone melatonin and the neurotransmitter serotonin, are a part of this process and are being studied for a possible role in SAD. Melatonin is secreted by the pineal glandpineal gland
, small organ (about the size of a pea) situated in the brain. Long considered vestigial in humans, the structure, which is also called the pineal body or the epiphysis, is present in most vertebrates.
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, which is in turn controlled by an area (the suprachiasmatic nuclei) of the hypothalamushypothalamus
, an important supervisory center in the brain, rich in ganglia, nerve fibers, and synaptic connections. It is composed of several sections called nuclei, each of which controls a specific function.
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; the hypothalamus, among other things, performs a clocklike function in the body. The eye's retinal nerves are connected to this area. Melatonin is secreted chiefly at night, and its secretion is suppressed by light. Secretion of the neurotransmitter serotonin declines in the winter and may undergo abnormal declines in those with SAD; concentrations of serotonin are increased by bright light. Serotonin is especially active in the hypothalamus. Decreased sensitivity of the retina has also been implicated as a cause of SAD.

Treatment with bright light (about five to twenty times brighter than normal lighting) often alleviates symptoms within a period of days. Unwieldy lighting paraphernalia has given way to smaller, portable light boxes and lighted visors. Doses range from 30 minutes to a few hours per day, often undergone in the morning to simulate the dawn.

seasonal affective disorder

[¦sēz·ēn·əl a¦fek·tiv dis′ȯrd·ər]
(psychology)
A syndrome of annually repeating depressive symptoms (usually overeating, oversleeping, and carbohydrate craving) that are related to changes in the season and are responsive to light therapy. Also known as winter depression.
References in periodicals archive ?
Roecklein's research data suggests that addressing, understanding, and managing these "unhelpful beliefs" about sleep by way of psychotherapy could lead to improved treatments for seasonal affective disorder.
Seasonal affective disorder is described in the book as one of the few psychiatric disorders that have a clear and identified biological cause.
People with seasonal affective disorder may benefit from spending more time outdoors and in front of windows, getting more exercise, and maintaining a balanced diet.
Schwabe Pharma UK, manufacturer of St John's Wort supplement KarmaMood, said the weather may have led to an increase in the number of cases of seasonal affective disorder (SAD).
92 % of the patients with severe seasonal affective disorder achieved full remission measured by the self-rated BDI-21 questionnaire.
Research has found that as many as one in eight Scots experience problems related to Seasonal Affective Disorder (SAD), the condition triggered by a lack of bright natural light.
Pets apparently want to eat more and exercise less and my veterinary colleagues believe they could be suffering from an animal version of seasonal affective disorder (SAD), caused by a build-up of the hormone melatonin.
Serotonin is a brain transmitter that helps keep our spirits up, and levels of it dip when sunlight is low and can frequently lead to Seasonal Affective Disorder.
This can be due to a condition known as Seasonal Affective Disorder, or SAD as it is more commonly known.
Rohan (University of Vermont) outlines 12 sessions for leading a six- week group program to help patients with seasonal affective disorder.
For one in 50 of us, however, low mood and fatigue can develop into a mild depressive condition called Seasonal Affective Disorder.
The shortest days are the worst time for those affected by the winter depression condition Seasonal Affective Disorder (SAD).