Seasonal Affective Disorder (Sad),sometimes known as the winter blues, is thought to affect around two million people in the UK and more than 12 million across northern Europe.
Its symptoms, described by the Seasonal Affective Disorder Association, can vary from depression, negative feelings often resulting in feelings of hopelessness and despair to numbness and apathy.
This leads to lethargy and difficulties in performing simple tasks. Some people will need more sleep while at other times they may have difficulty sleeping, plus problems staying awake during the day or waking at the correct time. Sufferers will struggle to remember or concentrate and the brain will not be as agile as desired. An unusual craving for sweet foods and carbohydrates can lead to weight gain which compounds the depression.
All these problems lead to irritability and antisocial feelings. Other concerns can include a weakened immune system so that sufferers are more susceptible to infections. There is often a loss in libido.
So why do many of us experience these symptoms? It has been estimated that 200 years ago, 75 per cent of the population worked outside in natural daylight. That figure has decreased to around 10 per cent. And modern life has totally changed our circumstances. We no longer rise at dawn, people work shifts, we travel long distances by air so that body-clocks are constantly altered, and electric light means that we often stay up late at night.
The UK is situated in one of the higher latitudes of the northern hemisphere and so light levels will change drastically from summer to winter. This is aggravated by periods of dark, murky weather when sufferers will notice aggravated symptoms.
A combination of all these problems, intensified by poor nutrition and bad weather plus increased demand for a faster lifestyle will result in dramatic effects on circadian rhythms.
What are circadian rhythms? In the past we took our cues from the sun and light which affected our body-clocks. We need good morning light to stimulate hormone activity which in turn wakes us and put us in a positive frame of mind. Without daylight we feel slothful and less industrious. And when it is time to sleep, because of the temptations of television and the computer, we extend our hours, exacerbating what is an already problematical situation.
A lack of natural light causes a reduction in serotonin which in turn causes us to become more depressed.
So to support the connected vital neurotransmitters in the brain, it helps to increase foods that naturally contain tryptophan (such as turkey, chicken, cottage cheese, bananas and avocado) which enables the body to produce seretonin. Supplements are also available but you should take medical advice before you start to take them. In the past, treatment has been with drugs but this is not now recommended as it is felt that drugs only help the symptoms rather than address the cause.
The website www.sad.org does recommend investigating a Sad light - a lightbox which simulates sunlight. Before using a light, sufferers should consult their doctors if they have eye problems, light sensitivity or have already been taking anti-depressants or medication. And then ensure that the box purchased has been recommended by the Sad Association, by the NHS, Bupa or other medical service providers with Sad experience. As the website points out: "Failure to do this could see you buying a product that is no more effective than a normal light bulb."
New clinical research suggests there is a link between low vitamin D levels and the occurrence of Sad - after all vitamin D is synthesised when the skin is exposed to sunlight. To optimise your vitamin D absorption in winter, you can take supplements or, if you can afford it, take a winter holiday.
Finally it is worth rethinking your diet. Omega 3 intake has been proven to support brain function. The simplest way to increase Omega 3 is to eat moreoily fish or flax- and pumpkin-seeds, supplementing this with wholegrains that contain generous amounts of B vitamins. Any weight gain can be balanced by eating more fruit and vegetables. If you combine this with plenty of exercise and the use of a genuine lightbox, you should see a huge improvement.