Seasonal affective disorder: What is it and how can you treat it?

Research claims that one in three people in the UK suffer from the condition during winter

Olivia Petter,Sophie Gallagher
Tuesday 29 September 2020 10:13 BST
(Getty Images)

The temperature is dropping, and the days are getting shorter as we head back into the winter months in the northern hemisphere.

Cue seasonal affective disorder (SAD): a type of depression that typically arises as we head into frostier climes.

Sometimes known as “winter depression”, according to the NHS, SAD symptoms are normally more apparent or more severe during winter rather than summer months. Few may have worse symptoms in summer and feel better in the cold.

It can be debilitating, leaving sufferers with a number of psychological symptoms, including irritability and a persistent low mood, as its acronym would suggest.

Here is everything you need to know about SAD, from what causes it to how it can be treated.

What is it?

SAD is a form of depression that people experience during a particular time of year, usually winter, though some sufferers may experience it in the summer months.

While it’s considered fairly normal for a person’s mood to be affected by the changing seasons, with people feeling notably cheerier when the sun is out and vice versa when it’s colder and cloudier, SAD is a recognised mental health disorder that can have a significant impact on someone’s day-to-day life.

According to research published in 2014, it affects 29 per cent of Britons in winter.

What causes it?

As with many psychological conditions, the exact cause of SAD isn’t known, but there are several theories as to why some people have more severe symptoms than others.

These are listed on the mental health charity Mind’s website, and include low serotonin levels, physical illness, a disrupted body clock and a change in diet or medication.

It’s also thought that people with SAD may have higher levels of melatonin, the hormone produced by the brain which makes us feel tired, which can leave SAD sufferers in a perpetual state of exhaustion.

What are the symptoms?

Symptoms of SAD vary from person-to-person, but according to the NHS, they can include: a persistent low mood, a loss of pleasure in everyday activities, feeling lethargic, sleeping for longer than normal and craving carbohydrates.

Some people may also experience feelings of guilt, despair and worthlessness.

How is it diagnosed?

If you think you have SAD, you’re advised to visit your GP, who will be able to carry out an assessment on your mental health.

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This may include asking questions about your mood, lifestyle eating habits and sleeping patterns and how these fluctuate with the seasons.

In some cases, they might also conduct a physical examination.

How is it treated?

The main treatments for SAD are talking therapies, such as counselling and cognitive behavioural therapy, and light therapy, whereby sufferers are encouraged to purchase a light box that simulates sunlight exposure - these are usually kept in people's bedrooms.

Some patients might also be prescribed antidepressant medication, such as selective serotonin reuptake inhibitors, which are also used to treat panic disorder and a number of phobias.

These work by increasing levels of serotonin in the brain, which many SAD sufferers will be lacking.

Other people may be encouraged to treat their condition with lifestyle changes, such as exercising regularly, eating a healthy diet and getting as much natural sunlight as possible by always trying to sit near windows and going for regular walks outside.

You can contact the Samaritans helpline by calling 116 123. The helpline is free and open 24 hours a day every day of the year.

You can also contact Samaritans by emailing The average response time is 24 hours.

For mental health info and support, visit, call 0300 123 3393, text 86463 or email

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