As we roll into autumn, many humans experience some sort of mood shift due to plunging temperatures and pushing back the clocks. It’s the time of year with shorter days, colder temperatures and sometimes bouts of the winter blues. Sluggishness, or just a desire to do nothing and hunker down indoors, is known as Seasonal Affective Disorder (SAD). No one knows for sure, but the same moodiness may affect your pet since we share much of the same chemistry in our brains. When darkness increases, the brain produces less serotonin (the happy chemical) and more melatonin (the sleep maker), so it is...