SAD The recent change in the weather has made us all feel a bit gloomy this week.
But psychologists are predicting an outbreak of people suffering from Seasonal Affective Disorder as the darker, colder evenings set in.
SAD is also know as the 'winter blues' as victims feel their symptoms begin with the turn of the season into Autumn.
In diagnosed cases, the symptoms can be so severe that they can cost people their jobs and break up relationships.[7 Habits To Better Manage Your Stress Day]
The effects vary from mild - tiredness during the day and over-eating - to very serious, such as joint pains, stomach upsets, loss of libido and even aggressive behaviour.
A further one in five of the population is thought to suffer a mild form of the disorder, known as sub-syndrome SAD. Many never bother to seek treatment.
SAD is triggered by a biochemical imbalance in the hypothalamus, the part of the brain that rules our body's main functions, such as sleep, appetite, sex drive, temperature, mood and activity.
When the days are long, natural light passes through the eye to the retina until it reaches the hypothalamus and stimulates these natural functions.
But if there is insufficient light, they begin to slow down and gradually stop - similar to a car running out of fuel.[Know The Causes of Short Term Memory Loss]
In recent years, however, there has been growing evidence that there are many ways to reduce the chances of developing SAD or even to prevent it.
So what is the best way to beat the winter blues this year?
Effective in up to 85 per cent of cases, light therapy is considered the best form of treatment for most SAD sufferers.
Special light boxes mimic the effects of the sun's rays by emitting enough brightness to penetrate the eye and stimulate the affected part of the brain.
Most people need to sit in front of a light box for one or two hours a day, although some suppliers provide special visors with lights attached, so it's possible to do household chores while getting treatment.
Ordinary domestic lights are nowhere near strong enough, at only 200 to 500 lux - the measurement of brightness. The minimum needed to treat SAD is 2,500 lux.
However, light boxes are not available on the NHS and can cost up to £200.
This therapy also uses artificial light - but this time it comes on very slowly in the morning to imitate a natural sunrise.
Special alarm clocks - called body clocks - come fitted with a light that can be set to take up to two hours to fill the bedroom with 'sunshine' while you're still asleep.
This speeds up the body's internal clock, so that the wakingup process begins before you open your eyes. Lights that come on quickly do not have the same effect.
SAD sufferers have found that dawn simulation helps regulate their body clock in the dark winter months, so they don't feel so lethargic in the day.
Research at the University of Washington School of Medicine last year confirmed dawn simulation worked in SAD. The special clocks cost £60-£100 each.
Exercise has become a proven aid in
SAD sufferers may have
disturbed sleep patterns
the treatment of mild depression. Now there's evidence it can help SAD victims, too.
A study by scientists at the Russian Academy of Medical Sciences revealed regular exercise - such as cycling for an hour a day - was almost as effective as light therapy in patients with the winter blues.
It's thought the benefits are produced because physical activity appears to stimulate feel-good chemicals in the brain.
Sunlight is the body's main source of vitamin D, and when levels are depleted in the winter months, some experts think it can increase the risk of SAD.
A study carried out in Baltimore, in the U.S., involving 15 SAD sufferers, showed that taking vitamin D supplements led to significant improvements in their mental health.
Apart from sunlight, other sources of vitamin D include fresh fruit and vegetables.
St John's Wort - a herb often referred to as Nature's Prozac - has proved effective for many SAD victims.
A survey last year by the Seasonal Affective Disorder Association showed it was a popular alternative treatment - twothirds of patients had used it and 40 per cent said it had worked.
However, side-effects were common, with many users reporting headaches, sore eyes and nausea. Worse still, it can cause a condition called photosensitivity, where the skin becomes irritated by any exposure to light.
SAD sufferers often crave refined carbohydrates, which can raise levels of serotonin - the moodaltering chemical found in the brain. But after a quick burst of energy, these can lead to sudden drops in blood-sugar levels.
Better to stick to protein-rich foods - such as turkey, chicken, salmon, kidney beans or lentils - and combine them with slowrelease complex carbohydrates, such as wholemeal breads or brown rice.
Normally reserved for phobias and trauma-related disorders, a non-drug treatment called cognitive behaviour therapy (CBT) has been found to help those with SAD. People who get depressed in the winter often get anxious about socialising and start avoiding friends and family as their condition starts to dominate their life.
CBT helps them examine all the triggers and face up to all their negative thoughts. Once they have done that, they are often better equipped to cope with the winter blues.