There's no proof that stress by itself causes long-term high blood pressure. But reacting to stress in unhealthy ways can increase your risk of high blood pressure, heart attacks and strokes. Prehypertension is between 120-139 for the first number in your blood pressure reading, and/or 80-89 for the second number. Nearly 30% of American adults have prehypertension, according to the CDC. What's the risk? You're more likely to get high blood pressure (hypertension).