As the days grow shorter, many people develop a type of depression called Seasonal Affective Disorder (SAD). Why does Seasonal Affective Disorder (SAD) cause xerostomia?

Due to depression, people have less desire to drink water, leading to dehydration and consequently, xerostomia

One of the treatments for SAD is the use of selective serotonin reuptake inhibitors (SSRIs), which cause dry mouth as a side effect

Shorter days mean people spend less time in sunlight, reducing exposure and causing dry mouth

Seasonal Affective Disorder causes xerostomia due to lack of specialist monitoring