For some people, winter marks the start of a relentless and recurrent cycle of depression that affects an individual's ability to function emotionally, physically and socially.
Known as Seasonal Affective Disorder (SAD), this condition is classified by the Diagnostic and Statistical Manual of Mental Disorders as a "specifier" in a major depression.
SAD is a type of depression that occurs at the same time of the year – either in winter or summer, but most often winter and so severely that it inhibits normal function.
Those with SAD experience episodes of major depression that tend to recur at specific times of the year, and these episodes may take the form of major depressive or bipolar disorders.
"SAD is so much more than just a feeling of seasonal sadness. It is a depression that presents with significant symptoms that are severe and persistent and recurrent, and prevent a person from performing basic functions during the season in which they are affected," Dr Theona Ballyram, a specialist psychiatrist who works at Akeso Clinic in Parktown says.
Symptoms of SAD include a feeling of depression, anxiety, hopelessness, lethargy, social withdrawal, changes in appetite and sleep patterns, as well as an inability to concentrate.
Although SAD is more often associated with the onset of winter, there are those who are similarly affected in the summer months - although Ballyram says the symptoms differ in how they manifest.
"Those affected by Winter Seasonal Affective Disorder tend to experience an increase in lethargy and appetite and an inability to wake up, while those affected by Summer Seasonal Affective Disorder tend to experience an increase in anxiety and insomnia, coupled with a decrease in appetite," she says.
Whichever way the condition presents, it can become crippling for sufferers - not least because of its tendency to remit and recur, a symptom that should make the condition easier to diagnose but can actually complicate diagnosis as patients feel that they are ‘better’ once the season comes to an end and thus often delay seeking help.
According to Ballyram, the disorder is not completely understood and there are several theories as to its causes, one of which even relates back to our ancestors hibernating over the winter months.
“What we do know is that there is a genetic component to the disorder, and it is definitely related to a disruption of the circadian rhythms and a dis-regulation of certain neural transmitters such as serotonin and hormones like melatonin,” she says.
The human circadian rhythm can be roughly explained as our internal clock, which is controlled by a variety of genes, but can be modulated by external cues such as sunlight and temperature. Serotonin is a well-known mood stabiliser, while melatonin plays an important role in determining eating and sleeping patterns.
For some people, a change in sunlight and temperature not only causes havoc with our internal body clock, but also results in a drop in serotonin levels, and a disruption of melatonin levels - all of which combine to create a severe depressive episode.
Ballyram says those who have a first-degree relative who suffers from depression or bi-polar disorder are also more at risk of suffering from SAD.
But the news is not all bad - once correctly diagnosed, SAD can be treated through a combination of therapies, including biological, psychological and psychosocial.
“There are a range of anti-depressants and mood stabilisers that have proven to be quite successful in the treatment of SAD, especially with the adjunctive use of melatonin and even the likes of light therapy,” says Ballyram.
She adds, however, that she believes it is imperative that anyone suffering from a mood disorder such as SAD should always take a multi-disciplinary approach to treatment, to ensure they are treating the condition holistically and not in isolation.
But perhaps the best news for South Africans is that SAD is not that common an ailment on our sunny shores.
“Yes, some people do suffer from SAD in South Africa, but it really is a condition that is more common in colder and darker climes,” says Ballyram.