Seasonal Affective Disorder (SAD)


This is a type of depression that is linked to the seasons. For most people with SAD, depression comes in fall and winter and goes away in spring and summer. But others have depression during the summer months.

Causes and Risk Factors

We don't know the exact cause of seasonal affective disorder. It may be linked to an imbalance of a chemical or hormone in your brain. It may be linked to low levels of vitamin D. This disorder is more common in young women. It's more common in people who live far away from the equator. Your risk is higher if you have a family history of depression. Your risk is also higher if you have another type of depression, or if you have bipolar disorder.


Seasonal affective disorder causes you to feel depressed most of the day, almost every day. You may have low energy levels and trouble sleeping. Things that you normally like to do may not interest you. You may have trouble concentrating, and you may feel hopeless or worthless. If your depressive episodes happen during the winter, you may tend to overeat, especially carbohydrates. You may withdraw from other people and sleep a lot. If your depressive episodes happen during the summer months, you may tend to have a poor appetite. You may feel restless and anxious, and you may have trouble sleeping. You may become violent.


There are medications that help lessen these symptoms. You may benefit from light therapy and from vitamin D supplements. Talk therapy may also be helpful. Your first step is to make an appointment. Your primary care doctor or a mental health professional will find the right treatment for you.