Seasonal affective disorder (SAD) is a rare mood disorder characterized by mood fluctuations that occur due to seasonal changes. It is particularly common in Northern European countries like Norway, Sweden or Finland. Most people with the disorder get depressed in winter and healthy during the summer months.

External linksEdit

  1. Better Health, warning this link is in PDF format
  2. MedlinePlus
  3. National Health Service
  4. PubMed Health
  5. WebMD