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Seasonal Affective Disorder (SAD)


Seasonal Affective Disorder (SAD) is a type of depression that occurs according to seasonal variation. It is most commonly seen during the winter months and less likely during summer. SAD is thought to be caused by changes in light exposure which can influence neurotransmitters and hormones such as serotonin and melatonin, as well as causing changes to our circadian rhythm.  


SAD is rare in Australia and more prevalent in countries in the Northern Hemisphere with less hours of daylight. It can occur at any age but usually begins to appear between 20 and 30 years of age, and is four times more likely to occur in women than in men.      



Symptoms start to arise late autumn and early winter and tend to worsen in the middle of winter. Symptoms are similar to that of common depressive disorder and may include:  

  • Decreased energy levels,  
  • Increased appetite particularly for carbohydrate rich foods,  
  • Weight gain,
  • Withdrawal from friends and family,  
  • Anxiety and irritability,  
  • Decreased sex drive.      


A diagnosis of SAD requires recurrent symptoms over a period of at least two years, occurring during winter and resolving during spring. It may be helpful to record your symptoms on a calendar so you and your health care professional can keep track of them.      



SAD symptoms usually resolve themselves over a week or so once winter has ended. Light therapy may be used whereby the individual is exposed to a specialized light box which mimics daylight. The light is thought to reduce symptoms by affecting serotonin and melatonin levels.  Antidepressant medications may also be prescribed if symptoms are severe.  


Other treatment options to help reduce depressive symptoms can be to participate in regular exercise, get as much sunlight as possible and have the support of your family and friends.  


It is important to take signs of SAD seriously. If not treated, depressive symptoms may worsen and lead to further complications such as suicidal thoughts and behaviours.      



The content displayed on this webpage is intended for informational purposes and is a guide only. It does not replace or substitute for professional medical advice, diagnosis or treatment. Information contained on this webpage must be discussed with an appropriate healthcare professional before making any decisions or taking any action based on the content of this webpage.      




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