Few of us relish the cold, dark days of winter. But for 7% of the British population, the chilly climes and lack of sunshine trigger a 'winter depression' called Seasonal Affective Disorder (SAD).
Although SAD affects a large number of people, with a further 17% suffering from milder symptoms, experts are yet to pinpoint exactly what causes the seasonal mood change.
Many experts believe it could be down to a biochemical imbalance in the hypothalamus, the part of the brain that controls mood and depression. This is controlled by the lack of natural daylight from the shorter, winter days.
Light exposure plays an enormous part when it comes to understanding SAD and how the body functions. When it's dark, the pineal gland in the brain produces the hormone melatonin, which makes us sleep; when it becomes light again, it stops producing melatonin and we wake up.
However, due to the lack of sunshine during the winter months, SAD sufferers have higher daytime melatonin levels, which subsequently cause sleepiness, lack of motivation and the desire to procrastinate.
"SAD is characterised by morning mood swings, low energy, increased appetite and weight gain, feeling withdrawn and passive," says Dr Robert Leahy, author of the Beat The Blues Before They Beat You. "I think of this as a 'hibernation' response since it mimics some of the same qualities of hibernation in animals residing in the cold climates."
Serotonin also plays a part in understanding SAD. Known as the feel good hormone, SAD sufferers tend to have low levels of serotonin during winter-time, mainly caused by the overproduction of melatonin making us feel sluggish and down in the dumps. During this period, our circadian rhythm (the body's internal body clock) is disrupted as a result, causing symptoms such as insomnia, lethargy and anxiety.
How common is SAD?
"Up to 38% of patients seeking treatment for depression have a seasonal component to their disorder," explains Dr. Leahy. "Generally speaking, 5% of the public have SAD and women are more likely to suffer from it than men." According to previous research, women are four times more likely to develop SAD than men.
What are the symptoms of SAD and when do they happen?
- Over-eating, notably with sugar and carbohydrate cravings
- Loss of libido
- Lethargy and inability to cope with daily routines
- Anxiety and pessimism
- Irritability and inability to tolerate stress
"Symptoms can occur at any age but usually appear between the ages of 18 to 30 years," says Consultant to Higher Nature and author of Nutrition Solutions for Optimising Female Health, Holly Taylor. "However symptoms can be made worse by other underlying conditions, such as fibromyalgia and chronic fatigue."
"Symptoms typically begin in September and increase in frequency over the next four months and reach a peak in January. The symptoms generally remain high in February and March, declining sharply in April and May," explains Taylor.
How can you beat the winter blues?
"Light therapy is often prescribed for patients with SAD," says Dr Leahy. "Bright light therapy helps wake you up in the morning and jump-start your circadian rhythms." The Royal College of Psychiatrists recently recommended 30 minutes of light therapy a day for SAD sufferers. "Also aim to spend more time outdoors as this maximises your exposure to natural sunlight," adds Holly Taylor.
However, light therapy isn't the only thing you can do to help combat the winter blues. Take a look at Holly Taylor's ten clever ways to beat the winter blues.