Your Health A-Z

Seasonal Affective Disorder

This is a form of depression strongly influenced by the seasons.

Alternative names

Winter depression, or summer depression. But was there ever a disorder with such an apt abbreviation – SAD?

What is it?

Winter depression begins in late autumn or early winter, and lifts with the arrival of summer; and summer depression runs from late spring or early summer until winter.

It seems to be linked to changes in the amount of sunlight during different seasons, and is more common in the far northern hemisphere, especially Scandinavia and other northerly lands. South Africans may experience it when migrating, for any significant amount of time, to countries in northern America or Europe.

It usually manifests in young people in their twenties, and becomes less common with age. Though some think it is related primarily to serotonin, like other forms of depression, there is a school of thought that believes a significant part is played by melatonin, which is produced by the pineal gland in dim light and darkness.


Primarily, the onset of depression coinciding with the start of a major season.

Other symptoms can include:

  • appetite change, with a preference for sweet and starchy foods, and weight gain;
  • fatigue, irritability, poor concentration, avoidance of social settings, and sleep changes (over-sleeping in winter, insomnia in summer; and
  • other typical depression symptoms including the loss of interest in and enjoyment of usual pleasures, amplification of aches and pains, and gloomy and hopeless feelings.
  • The history and symptoms are typical, and tend to come and go at the same time of year, each year, not usually related to other external life events, so diagnosis is usually straightforward.


    Apart from the usual treatments for depression (anti-depressant medication and cognitive-behavioural therapy), this condition is usually responsive to light therapy in the winter depression form. Depending on the technology available, one may wear a special light-delivering visor, or sit facing a bright light box or lamp, much brighter than normal indoors lighting, for some 30 minutes a day throughout the winter period. There are few side-effects, though some experience headaches or irritability.

    Tanning beds and similar equipment should never be used, as they provide the wrong type of light and have potentially serious side-effects.

    Moderate exercise helps pre-empt it, as does arranging to be outdoors in brighter light, especially on sunny days.

    SAD generally responds well to treatment. Untreated, it carries the hazards of any depression, including lasting misery and suicide risk.

    When to call your doctor

    Many of us are familiar with feeling blue during prolonged periods of dull weather. When you notice a pattern of more significant depression and weariness coinciding with the season, it is worth checking with a doctor.

    (MA Simpson, Health24, January 2008)

The information provided in this article was correct at the time of publishing. At Mediclinic we endeavour to provide our patients and readers with accurate and reliable information, which is why we continually review and update our content. However, due to the dynamic nature of clinical information and medicine, some information may from time to time become outdated prior to revision.

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