We refer to physical stressors--the tangible and measurable stressors -- as the tiger in your path: 1  accident/trauma. 2  alcohol in excess. 3  circadian light-dark cycle/rhythms. 4  food. 5  infection/virus. 6  injury. 7  medication. 8  seasonal change. 9  poison. 10  surgery. 11  temperature extremes. 12  tobacco. 13  toxin. 14  travel.