The research: Researchers from the University of Exeter Medical School analyzed blood pressure readings—taken by both a doctor and a nurse of the same patient on the same day—from more than 1,000 individuals across the world. The readings made by doctors were significantly higher (a whole 7/4 mmHg higher) than those made by nurses.  “This is a subconscious or reflex effect—sometimes dubbed the ‘alerting response’—caused by the taking of blood pressure,” says study author Christopher Clark. Your fight-or-flight response kicks in when the doctor tightens that cuff around your arm, which likely causes your blood-pressure reading to be higher than normal. And there’s actually a name for this phenomena by which your blood pressure rises when measured by a doc rather than a nurse—the white coat effect. Several other studies have shown it’s most pronounced in older females, particularly when they’re examined by a male doctor. And it occurs in a whopping 75% of patients with hypertension. What it means: A lot, actually. The difference was high enough to tip some patients over the high-blood pressure threshold, subjecting them to potentially inappropriate treatment. Short of busting out yoga moves in the waiting room, what can you do? “Sitting quietly is part of the routine for accurate blood pressure measurement and has been part of international guidance for many years,” Clark says. Avoid talking or moving during the measurement and hold the correct arm position. You can also limit the alert response by taking your blood pressure at home, says Clark.  The bottom line: Doctors are great for many a medical procedure, but they may not be the best people to take blood pressure, especially for patients with hypertension, says Clark. “Doctors should continue to measure blood pressure routinely as part of an examination, or in assessing an ill patient, but we believe that our findings demonstrate the risk of over-estimating blood pressure by doctors compared to nurses,” he says. Next time your white coat comes knocking to take your blood pressure, breathe deeply and think happy thoughts—this won’t hurt a bit.  More from Prevention: 13 Ways To Lower Blood Pressure Naturally