Blood pressure is the force exerted by blood against the walls of your arteries. It is measured with a rubber cuff that straps to your upper arm and is inflated against a pressure gauge. The air pumped into the device, a sphygmomanometer, is gradually released, and your blood pressure is measured with a stethoscope.

A blood pressure reading consists of two measurements — the systolic pressure and the diastolic pressure. When written or spoken, the numbers are referred to as one (the systolic) ‘over’ the other (the diastolic). The systolic reading reflects the pressure in the vessels during a heartbeat. The diastolic reading reflects the pressure in the vessel as the heart rests in-between beats.

A safe blood pressure reading for a non-smoking, non-over weight, healthy adult aged 18-45 with no history of heart disease is somewhere between 100/60 and 140/90. You can get your blood pressure read at mobile testing units, health fairs and pharmacists. But only your doctor can determine what is normal or safe for you.

Healthy blood pressure fluctuates during the day. It often goes up in the morning when you wake, or when you’re excited or scared. It sometimes drops during periods of inactivity, or when you sleep. Blood pressure also varies from person to person, depending on age, general health and other medical conditions.

A doctor therefore needs to know your normal blood pressure before she can determine if yours is high. It often takes several readings under different circumstances to get the right reading.

Some people have a history of high blood pressure and will suffer from the problem regardless of their physical health. But most bring it upon themselves by eating too much, smoking or consuming too much salt or foods high in cholesterol.

Cholesterol causes plaque to build up inside your arteries. The openings become narrower and narrower. Your heart has to pump the blood harder and harder in order to squeeze blood through the tinier hole. This puts more pressure on the artery wall — and increases your overall blood pressure.

Relief may come through a fatal stroke (if not enough oxygen reaches the brain) or a heart attack. There is no cure. The only alternative is prevention: You can modify your diet or lifestyle. High blood pressure is twice as common in people who are over weight. Switch to a low-fat diet and eat more calcium. Stop adding salt, cease caffeine consumption and stop smoking. And exercise.

There are no symptoms of high blood pressure as such, other than blood pressure readings themselves. Have your blood pressure checked every few months — perhaps more often if you’re at risk.