Seasonal Affective Disorder (SAD), also known as winter depression or winter blues, is a mood disorder in which people who have normal mental health throughout most of the year experience depressive symptoms in the winter or, less frequently, in the summer, spring or autumn, repeatedly, year after year. In the Diagnostic and Statistical Manual of Mental Disorders, SAD is not a unique mood disorder, but is "a specifier of major depression".
- Depression, feelings of gloom and despondency for no apparent reason.
- Lethargy, lack of energy.
- Anxiety, inability to cope.
- Social problems, irritability not wanting to see people.
- Sleep problems, finding it hard to stay awake during the day, and having disturbed nights.
- Loss of libido, not interested in sex or physical contact.
- Craving for carbohydrates and sweet foods, increased appetite leading to weight gain
Seasonal Affective Disorder or SAD has a lot in common with the hibernation cycle of animals and research has shown that this is triggered by a response to decreasing light levels. As the days grow shorter and the light becomes less intense, it increases the desire to 'hibernate'.
Light intensity is measured in 'lux' the Latin word for light. On a summer's day at our latitude we may have up to 16 hours of daylight at 100,000 lux. In winter an 8 hour dull day will give less than 5,000 lux and indoor lighting rarely exceeds 500 lux. All of our S.A.D. lightboxes are designed and manufactured by us to ensure that they produce 10,000 lux.