One of the most common areas that people come to see me about this time of year is Seasonal Affective Disorder (SAD). SAD was formally recognised as a variant of depression in the 1980s, however, The Royal College of Psychiatrists suggests that records of people suffering from low mood in the darker months go back as far as the 1800s.

SAD typically begins and ends at the same time each year and tends to deteriorate as the winter months progress. Research suggests it can affect an estimated 7% of the UK population every year, some people can spend over 40% of the year struggling with significant symptoms of depression and up to 35% of sufferers may require hospitalisation. I have seen how SAD can affect both children and adults and, in some cases, it can run in families. Research suggests SAD affects women more often than men and is more prevalent in populations further from the equator.

Research has not as yet uncovered the specific cause of SAD; however, a variety of factors are thought to play a part:

· Biological Clock (circadian rhythm). The decrease in sunlight over the autumn and winter months may disrupt our internal clock, resulting in symptoms of depression

· Serotonin levels. Reduced sunlight may also cause a drop-in serotonin levels. Serotonin is a natural brain chemical (neurotransmitter) which is important in regulating mood, appetite, and sleep. It makes us feel happy, motivated and enthusiastic and also supports memory, concentration and learning.

· Melatonin Levels. Reduced sunlight may also cause a reduction in melatonin, a hormone which is produced when it gets dark and makes us feel ready to sleep.