SAD is defined as "Seasonal Affective Disorder". Experience has shown that in winter most of the population eats and sleeps a little more and really dislikes dark mornings and short days. This phenomenon is referred to as "winter blues". On the other hand, the severity of this phenomenon depends on the individuals. Some people may be partially affected, yet others will have severe signs and symptoms such as trouble sleeping (insomnia), depression, anxiety, withdrawal, overeating, notorious fatigue, lethargy. All of this can often lead to a decline in multidimensional performance at home, at work and in relationships. This is a recognised problem known as Seasonal Affective Disorder (SAD).