Seasonal affective disorder (SAD) can arise when the seasons change, causing really low mood. People usually start to feel their moods change when winter hits and the daylight gets shorter and shorter. SAD affects about 1% to 2% of the population, while a milder form of winter blues may affect as many as 10 to 20 percent of people*.

The specific cause of SAD remains unknown but there are some aspects that may increase its appearance. The decrease in sunlight may affect your circadian rhythm or biological clock, which could lead to feelings of depression. Reduced sunlight can also cause a drop in serotonin which might also trigger really low mood. Melatonin levels can also be affected by the change in season, which may impact sleep patterns and mood.

Risk factors for SAD include:

  • A family history of SAD or another form of depression

  • Living far from the equator can be factor as there is decreased sunlight during the winter months.

  • Low levels of vitamin D may contribute towards SAD as vitamin D can help to boost serotonin activity.

Common signs and symptoms of seasonal affective disorder:

  • Loss of interest in activities you used to enjoy

  • Low mood

  • Low self-esteem

  • Feeling angry or stressed

  • Difficulty concentrating

  • Feelings of sadness and despair

  • Fatigue and lack of energy

Treatments for seasonal affective disorder can include:

  • Light therapy - it exposes people with SAD to a bright light to help make up for the reduced sunlight in the winter months.

  • Medication - to help improve a person's low mood

  • Psychotherapy - to help people manage their symptoms of SAD

  • Vitamin D - to help with symptoms

If you think you may be suffering from Seasonal Affective Disorder, you can talk to your GP, a psychologist or chat to a Sonder team member who can provide support and advice.


If you have any questions or need extra support, we're here to help you anytime, in any language. Simply start a chat with us via the home screen of the Sonder app.

* Information sourced from: Mayo Clinic, National Institute of Mental Health and Help Guide.

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All content is created and published for informational purposes only. It is not intended to be a substitute for professional advice. Always seek the guidance of a qualified health professional.

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