SAD, which affects an estimated half a million people, is normally at its height between December and February. Symptoms, which include lethargy, clinical depression and craving for carbohydrates, have persisted longer than that this year, and many more people, have developed milder forms of 'winter blues'. The condition is caused by a chemical imbalance in a part of the brain called the hypothalamus, triggered by the shortening of daylight hours. There is also evidence that osteoarthritis and other aches and pains of ageing get worse as rain approaches. As the temperature drops and humidity increases, the ends of the bones are thought to swell slightly, increasing pain.
Gloomy weather can also cause a dramatic fall in libido, psychologists say.
There is evidence that when it is overcast, hormones crucial to getting us in the mood for love are in short supply.