What is Seasonal Affective Disorder?

Seasonal Affective Disorder, often abbreviated as SAD, is a type of depression that follows a recurring seasonal pattern. While it can manifest during any time of the year, the vast majority of cases, approximately 90 percent, occur during the fall and winter months, leading to its colloquial description as the "winter blues. " This condition is not merely a fleeting feeling of low spirits that accompanies shorter days; it represents a significant and debilitating change in mood, energy, and overall functioning that substantially impacts daily life, work, and relationships.

The defining characteristic of SAD is its predictable timing. For a diagnosis to be considered, the depressive episodes must consistently begin and end at similar times each year. Typically, symptoms emerge between late fall and early spring, subside during the summer months, and then recur the following winter. The severity of the symptoms must meet certain criteria for a major depressive episode, such as persistent low mood, loss of interest in hobbies, significant changes in weight or appetite, sleep disturbances, fatigue, feelings of worthlessness or guilt, diminished ability to think or concentrate, and recurrent thoughts of death or suicide.

The scientific community largely agrees that the primary driver of winter SAD is the reduction in exposure to natural sunlight experienced during shorter days. This environmental change initiates biochemical changes within the brain, most notably affecting the circadian rhythm, also known as our “internal clock”. Disruptions to our circadian rhythm make it difficult to maintain a regular sleep cycle, further exacerbating feelings of depression.

Light therapy is one of the most popular ways of treating SAD. This involves exposing the individual to a specialised light box that mimics natural outdoor light. Patients are usually instructed to sit in front of the light box for 20 to 60 minutes daily, usually upon waking, to suppress morning melatonin production and effectively "reset" the circadian rhythm.

Seasonal Affective Disorder is a genuine and often severely limiting mood disorder rooted in the physiological responses of the human body to predictable environmental changes. Far from being a minor case of the blues, SAD involves measurable disturbances in hormonal balance and neurotransmitter function that require treatment. But with the tight therapy and some lifestyle changes, individuals with SAD can go on to live happy lives, all year round.

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