What is SAD?
‘Sad is a specific form of depression with specific symptoms only experienced in a particular season,’ says Beth Murphy, Head of Information at the mental health charity Mind, that affects around 17 per cent of people in the UK. The first sign is usually a drop in energy, which then gives way to lethargy. For some it is so severe that they find it difficult even to get out of bed in the morning.
Other symptoms can include a compulsive craving for carbohydrate-rich foods especially sugary snacks and chocolate, a lack of confidence, low concentration, anxiety, low libido and increased levels of irritability. ‘These can have a negative impact on other areas of life, putting pressure on relatonships and making it difficult to work or study,’ says Beth.
Who gets it?
SAD can affect anyone at any age although some studies suggest that women are more affected than men and that it is more common in people in their 20s. People with a family history of SAD may also be more susceptible. It occurs throughout the northern and southern hemispheres, but is rare in those living within 30 degrees of the Equator, where sunlight is constant and extremely bright.
What causes it?
There is no definitive answer as to what causes SAD, but lack of light is thought to be a major culprit. Light stimulates the hypothalmus – the area of the brain, which among other things contols mood, appetite and sleeping patterns.
It is thought that in people with SAD lack of light and an imbalance in certain brain hormones produced in the hypothalmus may trigger symptoms. This imbalance may be due to a faulty production of the feel-good hormone serotonin. Alternatively, it could be caused by increased levels of melatonin, the hormone that makes us drowsy so we fall asleep at night as darkness falls. ‘However, it can be hard to determine whether these hormonal changes are a cause or effect of the depression,’ says Beth. Research has also suggested that low levels of vitamin D, produced in the skin on exposure to sunlight, may be another contributory factor.
