A seasonal depression. Management of seasonal affective disorder.

1. SAD is a mood disorder characterised by recurring cyclic periods of autumn/winter dysthymia alternating with late spring/summer euthymia or hypomania. 2. It is now thought that SAD sufferers may be deficient in certain brain chemicals, and it is likely that the interactions of a number of neurotransmitters are responsible for the disorder. 3. In the UK, 72% of SAD sufferers report an increase in sleep from around seven hours in the summer to nine in winter. 4. Phototherapy has been proved an effective treatment for SAD, and lamps for phototherapy are becoming increasingly available.