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Seasonal affective disorder – does it exist?

Seasonal Affective Disorder

We all get a touch of the winter blues when the days get shorter and the weather gets cold. For people with seasonal affective disorder (SAD), this low can take the form of a debilitating depression that can interfere with their working life and relationships, leading to serious mental health problems. Seasonal affective disorder is also quite controversial; people affected by depression in the winter are convinced it is a real health condition but some health professionals are less sure.


This article on seasonal affective disorder is written by Kathryn Senior, a freelance journalist who writes health, medical, biological, and pharmaceutical articles for national and international journals, newsletters and web sites.


What is seasonal affective disorder?

Seasonal affective disorder is defined as depression that comes and goes with the changing seasons. It is most often experienced during the winter months, starting in September and those affected report that it peaks in January and February before easing as spring arrives. Some people claim to be affected by seasonal affective disorder only in the summer months, but this is much rarer.


In the UK, seasonal affective disorder is estimated to affect around 5% of the population – that’s 3 million people. Many of these only experience fairly mild symptoms, known as the ‘winter blues’ or sub-syndromal seasonal affective disorder.

What are the symptoms of seasonal affective disorder?

As with any depressive illness, seasonal affective disorder has a range of symptoms that vary from person to person and in terms of their individual severity. The main symptoms that people with SAD have reported include:

  • Sleepiness and lethargy – oversleeping but not feeling refreshed and feeling tired all the time
  • Overeating – constantly craving comfort foods such as carbohydrates.
  • Depression – feeling miserable for no reason, worrying and despairing
  • Illness - low resistance to infection leading to many minor illnesses, which can make the other symptoms worse


Seasonal affective disorder can lead to social problems, including family and relationship problems, as those affected become irritable and moody and lose interest and enthusiasm for life.


Why is seasonal affective disorder doubted?

Seasonal affective disorder is sometimes doubted because the symptoms are fairly general and can be attributed to other causes. Some experts think this is not a real syndrome but a normal response to the seasons. None of us enjoy getting out of bed on a cold, dark winter morning, and most of us have much more enthusiasm for life when the sun is shining and the weather is warm. It is possible that seasonal affective disorder is just an over reaction to these natural feeling, rather than a genuine medical and psychological condition.


What causes seasonal affective disorder?

As there is doubt surrounding the condition, research into seasonal affective disorder is still in its early stages. Those convinced it does exist suggest that the lack of sunlight during the winter months reduces the level of hormones produced in the brain by the hypothalamus. Data on the geographical distribution of people with seasonal affective disorder sufferers supports this. There are more people reporting SAD as you move away from the equator except in places that have snow on the ground as the reflective quality of the snow increases the intensity of the light, even in winter.


The lack of light stimulus affects the brain by:

  • Increasing melatonin production. The hormone melatonin regulates sleep. When the hypothalamus detects light, it sends a signal to the pineal gland to reduce the production of melatonin so that you wake up in the morning. In people with seasonal affective disorder, the lack of light leads to a raised level of melatonin, which can make you constantly tired.
  • Decreasing serotonin production. Serotonin is a hormone that regulates moods, appetite and sleep and that is produced by the hypothalamus when it detects light. Lower light levels in winter result in generally lower serotonin levels that could cause some of the symptoms of seasonal affective disorder.
  • Disrupting sleep patterns and natural circadian rhythms. People with seasonal affective disorder often report disturbed sleep patterns and unusual tiredness through the day.

Who gets seasonal affective disorder?

As in most other forms of depression there are often mitigating factors that make one person more susceptible to SAD than another. These include:

  • General mental and emotional health
  • A family history of depression or mental health problems
  • Personal circumstances at the time
  • Emotional history


Treating seasonal affective disorder

The NHS recommends that seasonal affective disorder is treated in the same way as any other form of depression, using either psychosocial treatments or anti-depressant drugs, or a combination of both.


Psychosocial treatments include techniques such as cognitive behavioural therapy. This is a counselling-based therapy in which your responses to situations and your behaviour patterns are discussed in depth, in either one to one or group sessions. The aim of the therapy is to help you to identify your behaviours and consciously change the way they make you feel.


Anti-depressant drugs are aimed at countering the chemical changes that are thought to occur in the brains of people with seasonal affective disorder. The most commonly used drugs are selective serotonin reuptake inhibitors, such as Prozac. These prevent the body from reabsorbing the serotonin the body produces, maintaining a higher level.


Some people with SAD favour using light boxes to artificially replace the missing sunlight during winter months, but the evidence that this works is far from conclusive. What’s more, these light boxes must be powerful – around five times brighter than a well lit office – and someone with seasonal affective disorder must sit beside them for up to half an hour a day to get any benefit.


Kathryn Senior

Profile of the author

Dr Kathryn Senior is an acclaimed medical journalist who has written over 500 feature articles for leading international journals within The Lancet group. As Senior Writer at Freelance Copy she produces high quality scientific and medical content for websites and printed publications for companies and organisations in the health, medical and pharmaceutical sectors. 


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