Winter SAD’s onset is associated with the changing of the seasons and the cold weather, being stuck indoors, shorter days and less sunlight exposure. However, Dumler said, there is a correlation between extreme heat and agitation. People on psychiatric medications such as antidepressants or mood stabilizers, for example, may have more difficulty regulating their body’s temperature, she said.
Warm-weather SAD is less common and tends to show up as anxiety, agitation, insomnia, and weight loss, while winter SAD is more tied to fatigue, oversleeping, weight gain, low energy, and social withdrawal. Winter symptoms are driven by shorter days, cold weather, and reduced sunlight, but Dumler notes that extreme heat can increase agitation, especially for people on psychiatric medications that make temperature regulation harder.