Fact 1: When the seasons change from the summer to the fall , the amount of daylight will decrease.

Fact 2: Symptoms of their depressive illness are worsened by decreased daylight.

Given the two facts above, answer the question "When the seasons change from the summer to the fall, symptoms of what will sometimes worsen?" with the following options: 
- vitamin D excess
 - hypothyroidism
 - Dehydration
 - direct damage to the lungs
 - Thanksgiving
 - green
 - Abnormal cell growth
 - depressive illnesses


 

        depressive illnesses 