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Do You Have Seasonal Affective Disorder?


Tom Hale


Tom Hale

Senior Journalist

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

3616 Do You Have Seasonal Affective Disorder?
Mycroyance/Flickr. (CC BY-NC 2.0)

As the hours of sunlight creep away and we seem to be forever fighting off colds, we can all come down with a case of the “winter blues.” However, for some people, the winter brings a serious and debilitating illness called Seasonal Affective Disorder (SAD).

SAD is a specific type of depression that comes and goes in seasonal patterns, usually starting in autumn and gaining momentum through the winter.


It comes with the same symptoms as depression: a persistent low mood, increased desire to sleep, constant tiredness, a lack of interest in the outside world (apathy), irritability and feelings of low self-esteem and despair. However, for most people, the symptoms appear to lift around spring time.

Accordingly, SAD is most common in Scandinavia, Europe, North America, Southern Australia and North Asia – where the decline in daylight hours are most severe during winter. As such, it is very rare to find someone suffering from SAD who lives near the equator. To illustrate this, one study found SAD's prevalence in the United States ranges from 1.4 percent in Florida to 9.9 percent in Alaska.

Like all mental illnesses, there is a spectrum of severity. We can all expect to feel a little glum during the post-Christmas hangover when you just want to be on a hot beach, but SAD is a different type of beast all together.

In the U.K., about 20 percent of people can experience mild symptoms, called “sub-syndromal SAD.” However 2 percent can experience severe symptoms, which can seriously reduce their ability to function in everyday life.


Image credit: Isengardt/Flickr. (CC BY 2.0)

There are a few theories of what exactly causes SAD, although it is largely thought to revolve around our mind and body’s reaction to the lack of sunlight. Some propose that the decline in sunlight hours messes with our internal body clock, or circadian rhythm, causing us to experience symptoms of low energy. Studies have even gone as far to suggest this reaction is actually not too different to our animal counterparts slumping into hibernation during winter.

There are also ideas surrounding the role of sunlight and our body's production of melatonin and serotonin. Melatonin is a hormone that helps regulate our sleep cycles. Darkness causes the body to produce more melatonin, which signals the body to prepare for sleep – hence that constant lethargic feeling many get during the winter months. The production of serotonin, the chemical transmitter associated with mood, happiness and serenity, is also affected by sunlight. Not only is it only produced during the day, but we convert it into melatonin during darkness.

But SAD isn’t just a pit of despair, there’s many things you can do to tackle it. Simple lifestyle changes, such as getting out in the sunlight as much as possible and regular exercise, are used to tackle it.


Many doctors will also recommend counselling, cognitive behavioural therapy (CBT) or taking specific type of antidepressants called selective serotonin reuptake inhibitors (SSRIs), which help boost the amount of serotonin available in the brain.

Most interestingly, some SAD sufferers use special lights which – unlike domestic light bulbs – emit a light more akin to natural sunlight. These are fairly accessible online or, if you're strapped for cash, you can even rent them in some areas of the world. Recently, people have also experimented with taking vitamin D supplements, since this is produced upon our skin's exposure to sunlight, although studies have shown mixed levels of success.

So if you've been feeling run down with a bad case of the "winter blues," it is probably not just your imagination. However, there's also a lot you can do to find that "invincible summer" which lies within you. And, of course, if it's really affecting your day-to-day life, it's best to consult your doctor. 

Main image credit: Mycroyance/Flickr. (CC BY-NC 2.0)


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  • sunlight,

  • winter,

  • sad