What condition is characterized by depression with specific seasonal patterns?

Seasonal affective disorder (SAD) is a subtype of major depressive disorder specifically marked by recurring episodes of depression that occur during certain seasons, typically in the fall and winter months when there is less natural sunlight. The symptoms include feelings of sadness, lethargy, and changes in sleep and appetite, which significantly improve during the spring and summer months.

This condition is thought to be related to changes in light exposure, affecting the body's internal clock and melatonin levels, leading to changes in mood and behavior. Understanding the seasonal pattern is key in identifying SAD, as it distinguishes it from other forms of depression that do not have this specific time-related characteristic.

This clear seasonal pattern is what solidifies SAD as the correct diagnosis in this question, differentiating it from other mental health disorders that do not exhibit this pattern, such as generalized anxiety disorder, which is characterized by chronic, excessive worry; major depressive disorder, which can occur without any seasonal reference; and post-traumatic stress disorder, which is related to experiences of trauma rather than seasonal changes.