Understanding SAD — the science behind the winter blues

Whilst most of our winter months are filled with festive fun, some of the population struggle with seasonal depression. In the latest blog from SRG, we uncover why.

It’s the middle of December, the days are short, the nights are long, the shortest day of the year is just a week away. People up and down the country are getting exciting about the prospect of spending time with friends and family over the Christmas break. For most, the anticipation of mulled wine, turkey and sitting in front of the TV is enough to beat away the darkness.

But for the 6% of the population in the UK who suffer with seasonal affective disorder (SAD), this time of year can be a living nightmare. Symptoms of SAD can include feeling anxious, hopeless, occasionally leading to major depressive episodes. It can even lead to serious suicidal thoughts. Though the winter blues can feel like something of a myth, or simply being under the weather, SAD is a serious clinical depression that often goes untreated.

Why do we get SAD?

Most theories link SAD to circadian rhythms. Decreased exposure to bright light during the autumn and winter can — in SAD sufferers — drive the production of melatonin, which subsequently drives the lethargy and depressive symptoms commonly associated with the condition.

The morning sun is our natural alarm. When our eyes detect sunlight, a signal is sent to the suprachiasmatic nucleus — our circadian clock. It informs our pineal gland to inhibit the secretion of melatonin. When there is no light when we wake up in a morning, it tricks our brain into thinking that it’s still night time. This also explains why we get tired earlier during winter months.

It is unsurprising to discover that in countries closer to the poles, such as Canada and Norway, the percentage of people who get SAD is higher. In Alaska, for example, where days are endlessly dark in the winter, occurrences of SAD in the population can reach to 10%. 

Serotonin deficiency

Production of serotonin is also thought to have an impact on seasonal affective disorder. Studies show that serotonin, a neurotransmitter that regulates mood, may also be modulated by light.

Though we don’t know exactly how reduced sunlight leads to lower levels of serotonin, there are increasing numbers of studies seeking to discover the direct link. According to the Pfizer blog, Get Science, brain scan studies indicate that:

“people with SAD had higher levels of a serotonin transporter protein (SERT) in the winter compared to healthy individuals. The more SERT a person has in his/her brain, the less the mood-enhancing neurotransmitter is freely available, causing people to more likely to experience symptoms of depression.”

The gender divide

Interestingly, women tend to get SAD at much higher rates than men. About 80% of people who suffer from seasonal affective disorder are women between the ages of 18-45. This could be related to hormonal differences between the sexes.

However, some researchers suggest that SAD is a remnant of adaptive behaviour to protect pregnant women in the winter months during the Ice Age.

Another impact could be that — despite increasing awareness of mental health issues — men are less likely to consult with a mental health practitioner which could somewhat skew the numbers. Whatever the reason, SAD is an issue that predominantly is lived out by women.

Light therapy

For both melatonin and serotonin, the treatment for most people with SAD is light therapy. As light cues get weaker deep into the winter, a common solution is to use a light box for 30 minutes at a time which imitates natural light — allowing the body clock to recalibrate. Most people respond well to this non-invasive therapy.

Some countries are tackling the issue head on. Sweden, for example, which sees very little natural light during winter months, has converted bus stops to emit light which can help to treat SAD.

For people who feel blue in the winter months, rather than those with SAD, simply exposing yourself to light by having a walk in the middle of the day can have a positive effect. Whether done every day, or a few times a week, it can give you the mood boost necessary to beat the winter blues. Exercise, too, can have a positive impact on mental health. For everyone living in the UK, taking a walk on your lunch break might just make winter blues more manageable.

If you feel like you are suffering from SAD, or any other mental health issue, please seek advice from a medical professional.

For more fascinating insights into the ever-changing world of the life sciences sector, stay tuned to all SRG Blogs.

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