Seasonal Affective Disorder (SAD)

Seasonal Affective Disorder (SAD): Depression Symptoms Guide

This article is part of the Depression Symptoms Guide. In this part of the series, we will examine the type of depression known as Seasonal Affective Disorder (SAD).

SAD is a type of unipolar disorder, often also referred to as winter depression, winter blues, seasonal depression or seasonal mood disorder. It is a depressive disorder which causes people who are typically mentally healthy, to experience depressive symptoms during the winter (and sometimes other seasons), repeatedly and at the same time each year.

A variant of SAD affects people during the summer (and sometimes spring) months, referred to as Reverse Seasonal Affective Disorder (RSAD), or summer-onset depression.^[1]

Seasonal effective disorder is believed to be related to light, one argument for this being the effectiveness of bright light therapy in treating the condition.^[2] SAD is significantly more common in the northern hemisphere where winters are longer and harsher, particularly the Nordic countries and Alaska.

The SAD rate in Alaska is approximately 8.9%, and 24.9% for subsyndromal SAD (‘Sub-SAD’, a minor form of seasonal affective disorder).^[3] In Ireland an estimated 20% of people are affected by SAD, and 10% in the Netherlands^[4], and as with both major depressive disorder and dysthymia, women are more likely to affected by SAD than men.

Surprisingly, in Iceland seasonal affective disorder is significantly less common than in other Nordic countries, and it has been suggested that this may be due to the large amount of fish traditionally eaten by people in Iceland.^[5]

Fish is both high in vitamin D (with another source being sunlight), and also contains docosahexaenoic acid (DHA), which has been shown to help with a variety of neurological dysfunctions.^[6]

Symptoms

The symptoms of seasonal affective disorder can be similar to dysthymia and major depressive disorder, the latter of which many SAD sufferers will also experience during the term of their illness.

Symptoms of the condition can vary depending on the type of SAD being experienced. For winter and autumn seasonal affective disorder, symptoms may include:

A generally depressed or pessimistic mood.
Hypersomnia.
Overeating, and often weight gain caused by a craving for food high in carbohydrates.
Difficulty concentrating on and completing tasks.
Loss of energy.
Withdrawal from friends, family and social activities.

In cases of spring and summer seasonal affective disorder, symptoms may include:

Anxiety.
Insomnia.
Decreased appetite, possibly accompanied by weight loss.
Irritability.
Agitation.
A decreased interest in sex.

In cases of reverse seasonal affective disorder (RSAD), symptoms may include:

Constantly elevated mood.
Hyperactivity.
An increase in social activity.
A sense of enthusiasm or elation which is out-of-proportion to the situation.

Diagnosis

Seasonal affective disorder is sometimes misdiagnosed as hypothyroidism, hypoglycemia, infectious mononucleosis, or other viral infections, so diagnosis often begins with a series of medical tests to rule out these and other conditions that may explain the sufferers symptoms.

According to the DSM-IV-TR^[7], SAD is not regarded as a separate depressive disorder, but rather a ’seasonal pattern specifier’, or subtype of major depressive disorder or bipolar disorder. The seasonal pattern specifier must meet the following criteria for a diagnosis of seasonal affective disorder to be made:

The presence of depressive episodes at a particular time of year, for at least two years during the same season each year.
Remissions or mania/hypomania also at a specific time of year.
No other type of depression, or other medical condition better explains the changes in mood or behaviour.

Getting Help

If you feel you are suffering from seasonal affective disorder, it is important to seek medical help quickly. Seasonal affective disorder, if left unchecked can develop into more-serious depressive disorders, but if identified early the condition has a highly successful treatment rate.