What is a disorder that is a form of depression typically experienced in the fall and winter when light levels are lower?

The disorder you're referring to is Seasonal Affective Disorder (SAD), a type of depression that occurs at specific times of the year, most commonly in fall and winter when daylight hours are shorter. Individuals with SAD may experience symptoms such as low energy, mood changes, and difficulty concentrating. Treatment options often include light therapy, psychotherapy, and medications. The condition is thought to be linked to changes in light exposure affecting circadian rhythms and serotonin levels.