Causes of seasonal affective disorder - SAD - winter depression

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The causes of SAD are not fully understood but factors like living in higher latitudes, reduced daylight, low temperatures, hormone regulation and short days seem to be causes the disorder.

Bright light induces certain chemical changes in brain and stimulates hypothalamus, a part of the brain responsible for controlling sleep, appetite and mood.

Lack of sufficient light reverses the chemical process in the brain affecting our mood, sleep and activeness. These changes lead to SAD depression.

Disturbed circadian rhythm and SAD disorder

Circadian rhythm or our biological clock regulates our sleep and wakefulness.

The reduction of daylight in fall and winter disrupts the sleep pattern causing depression.

Reduction in the levels of serotonin and SAD depression

Serotonin is a natural chemical found in the brain which being a neurotransmitter has the ability to affect our sleep, appetite and mood.

The levels of serotonin are affected by sunlight and reduced daylight means reduced production of serotonin.

This results in the ineffective transmission of signals from the nerves to brain and causes the disorder.

Affected persons produce less serotonin in fall and winter.

Increase in the secretion of melatonin

Melatonin, a hormone produced by the pineal gland in the brain controls our sleep pattern.

In darkness the gland produces melatonin, helping us to sleep.

In the daylight the production of the hormone is reduced and we wake up. Persons affected by winter blues have been found to produce more melatonin in the reduced sunlight period.

Genetic causes of SAD

Possibility of genetic transmission is suggested in the results of research work on this disorder.

Close relatives and siblings of the SAD patients have been found to develop this depression.

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SAD - Seasonal Affective Disorder - Winter Depression

Home > SAD - Winter depression

SAD, which is also known as winter depression is a medical condition causing depressed moods with the advent of shortened daylight in fall and winter.

SAD is a form of mood depression occurring in relation to the changing seasons especially with the beginning of fall and snow fall. The same persons are active and normal during rest of the year.

In some rare instances SAD occurs in some individuals in spring or in early summer and is called Reverse SAD.

This winter disorder  is more common in people living in higher latitudes away from the equator. Its occurrence is linked to colder and shorter days. It often occurs in the same time year after year.

Signs and symptoms of SAD start around the beginning of September and get worse in the months of December, January and February when the days are shortest.

With the onset of spring, usually, the condition improves and winter disorder symptoms disappear.

The person with depression blues feels lethargic, tired, depressed, stressed, sleepy, unhappy and less sociable. He has little energy and craves for starchy foods and sweets.

In United States nearly 10% of the population may be suffering from SAD. Up to 10% of Alaska residents suffer from this disorder.

In UK up to 10% of the population is affected by various degrees of SAD.

It is estimated that Netherlands has up to 10% of its population suffering from SAD.

An estimated 20% of Irish population suffers from this disorder.

Greater number of people may be suffering from subclinical and sub-syndromic disorder.

This disorder affects twice the number of women than men. Though persons of all age groups can be affected this mood depression is more common among the age group of 20-30 years.

Very rarely children and young adults below 20 years are affected by this depression. With old-age the risk of SAD decreases.

It is also found that many of the affected persons have one or more close relatives and siblings with psychiatric conditions, pointing to the possibility of genetic and hereditary angle for this winter disorder.

SAD - bright light therapy lamp (enlarge)

There are a number of medications and treatments available now for treating this depression.

Light therapy with exposure to bright lights, administration of ionised air, psychotherapy, antidepressant medicines and melatonin hormone supplementation have been found to be effective in treating winter SAD.

Related topics:
Bright light therapy.
Causes.
Signs and symptoms.
Diagnosis.
Treatment and therapy.

Current topic:
SAD depression and winter.

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