Seasonal Affective Disorder (SAD) is a type of depression that occurs during the fall and winter months when there is less natural sunlight. It is also known as winter depression or winter blues. The symptoms of SAD usually start in the late fall and can continue until spring when the days get longer.

The signs and symptoms of SAD are similar to those of depression, but they occur in a seasonal pattern. These symptoms may include:

• Low mood, sadness, or hopelessness
• Loss of interest in activities
• Low energy and fatigue
• Difficulty sleeping or oversleeping
• Difficulty concentrating
• Changes in appetite, especially craving for carbohydrates
• Weight gain

Diagnosing SAD involves assessing the presence and severity of the symptoms, as well as their seasonal pattern. A healthcare provider may ask about the onset and duration of symptoms and may also use questionnaires or interviews to help make a diagnosis. They may also perform a physical examination and run blood tests to rule out other medical conditions that can cause similar symptoms.

The exact cause of SAD is not known, but it is believed to be related to the changes in the amount of sunlight that occur during the fall and winter months. The decrease in sunlight can disrupt the body's internal clock, leading to hormonal imbalances that affect mood and energy levels. Certain factors may increase the risk of developing SAD, such as living far from the equator, having a family history of depression, or having a preexisting mental health condition.

Treatments for SAD may include light therapy, which involves using a specialized lightbox that emits bright light to mimic natural sunlight. This can help reset the body's internal clock and improve mood and energy levels. Other treatments may include talk therapy, medication, or lifestyle changes such as regular exercise, a healthy diet, and stress management techniques. It is important to talk to a healthcare provider about the best treatment options for individual needs.