What is Seasonal Affective Disorder?

The seasons can affect us a great deal more than we realise. In a warm climate country, like Australia, it’s natural that you feel your mood drop a little when the mercury starts to fall, but for some people, the change of season can herald something more serious, and even bring depression. Relatively few Australians suffer from Seasonal Affective Disorder per capita, but for those that do feel the symptoms, the turning of the seasons can be devastating. 

Seasonal Affective Disorder: Symptoms

Seasonal Affective Disorder (sometimes referred to as SAD) is a form of depression that comes and goes with the seasons . For the majority of sufferers, Seasonal Affective Disorder appears in the colder seasons , where autumn and winter are the trigger, but for some (around 10% of sufferers, and those living closer to the equator) it is spring and summer. 

Depending on the season that triggers it, the symptoms can vary:


  • Constant tiredness/fatigue
  • Craving carbohydrates
  • Difficulty waking in the morning
  • Feelings of hopelessness and sadness
  • Hypersomnia - sleeping too much
  • Lack of initiative/interest
  • Weight gain


  • Anxiety and agitation
  • Difficulty sleeping/insomnia
  • Lack of appetite
  • Weight loss

For most people with SAD, the anxiety and depression are relatively mild, but some sufferers may develop major depression. 

What Causes SAD?

While the exact cause of Seasonal Affective Disorder is not known, there are a few theories as to why seasonal change may affect people’s mental state. One major theory is that the change in season can affect the body’s circadian rhythm (the body clock), changing sleep patterns, energy levels and the production of different hormones and enzymes. 

For those who experience SAD during the winter months, it may be attributable to the fact there is less sunlight at that time of the year. Less exposure to sunlight means that the body produces less melatonin and serotonin, and these two hormones can affect both sleep and mood. 


Given that the lack of exposure to sunlight seems to be one of the major contributing to winter Seasonal Affective Disorder, it’s no wonder then that one of the most effective treatments for the condition is phototherapy - exposure to a special light box on a daily basis. Typically a person with SAD will sit in front of a light box that mimics outdoor light for 30-60 minutes each morning until the seasons change. 

While phototherapy appears to be the most effective overall treatment for SAD, depending on the severity of symptoms, and the levels of depression or anxiety, counselling and medication may also be needed. Vitamin D supplements have also been shown to be effective in reducing symptoms in some cases.  

If you believe you may have Seasonal Affective Disorder, the easiest way is to search for a doctor and book an appointment online with MyHealth1st. 

What Should I Do if I Think I Have SAD?

If you find yourself becoming anxious or depressed around the same time every year and find your mood spiralling out of control particularly at the change of seasons, you may have Seasonal Affective Disorder. Keeping track of your symptoms can aid with diagnosis, so try to note them in a diary that also records the date. If you find you do have a mood change that occurs in winter, ensure you get adequate exposure to sunlight and make sure you plan enjoyable activities during the winter months can potentially help alleviate symptoms. If you have the effect in summer, try to note the thoughts about this period e.g. body issues, heat etc. and plan ahead to manage them. For example, you can plan your holidays to avoid having to swim, or be in a cooler place rather than go to the beach.

Due to the cyclical nature of SAD, diagnosis can be difficult as it may take years to discover or show that you have an ongoing pattern. If you believe you may have Seasonal Affective Disorder you should make an appointment with your doctor. Your GP may wish to do some testing to rule out medical causes that have similar symptoms, such as hypothyroidism or a seasonal viral infection.

Ask your doctor to prepare a Mental Health Care Plan for you. This plan allows you to access up to 10 sessions with a psychologist that can be bulk-billed.

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